incorrect error message creating snapshot from share that does not support it

[Tom Barron]

Description
===========
When attempting to create a snapshot from a share that does not support snapshot creation, the user gets a message like the following:

ERROR: Snapshot cannot be created from share 'f95eb067-d111-4238-bd46-7cb0fba07f43', because share back end does not support it

The message is incorrect in that the actual share back end may well support snapshot creation but the share was created using a share-type without the 'snapshot_support' extra spec set to True. Without this, the share created will have its snapshot_support property set to False and snapshots cannot be created from it irrespective of the back end capabilities.

This message also violates the principle that back end information is not for regular manila users rather than cloud administrators.

Steps to reproduce:
==================
  Deploy manila with a single backend that supports snapshot creation (or multiple backends, all of which have such support). Turn on debug so backend capabilities are shown in the periodic reports to the scheduler log.
  Check the scheduler log and observe that the backend(s) report snapshot_support = True.
  Create a share type without snapshot_support set at all.
  Create a share from the share type.
  Show the share and observe that it has snapshot_support=False.
  Attempt to create a snapshot from the share and see that it errors with a message claiming that the share back end does not support snapshots.

Expected result:
===============
Error message should say that the source share does not support snapshot creation rather than that the back end doesn't.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/manila/+/787371

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/787371
Committed: https://opendev.org/openstack/manila/commit/be29805859f0e759cfd96b5e1ef0afbd1d16f3c0
Submitter: "Zuul (22348)"
Branch: master

commit be29805859f0e759cfd96b5e1ef0afbd1d16f3c0
Author: Tom Barron <email address hidden>
Date: Wed Apr 21 09:38:33 2021 -0400

    Fix api error message for snapshot creation failure

    when the source share has ``snapshot_support`` False.

    The message said that the back end lacks snapshot support but this
    is not necessarily the case.

    Closes-bug: #1925342
    Change-Id: I09a83b63528c0988f3601dfd07ad6972165cb855

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/wallaby
Review: https://review.opendev.org/c/openstack/manila/+/791108

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Tom Barron <email address hidden>" on branch: stable/wallaby
Review: https://review.opendev.org/c/openstack/manila/+/791108

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/791108
Committed: https://opendev.org/openstack/manila/commit/fb5a4f936d6ecf7435005f72ef8d7068cf75f65e
Submitter: "Zuul (22348)"
Branch: stable/wallaby

commit fb5a4f936d6ecf7435005f72ef8d7068cf75f65e
Author: Tom Barron <email address hidden>
Date: Wed Apr 21 09:38:33 2021 -0400

    Fix api error message for snapshot creation failure

    when the source share has ``snapshot_support`` False.

    The message said that the back end lacks snapshot support but this
    is not necessarily the case.

    Closes-bug: #1925342
    Change-Id: I09a83b63528c0988f3601dfd07ad6972165cb855
    (cherry picked from commit be29805859f0e759cfd96b5e1ef0afbd1d16f3c0)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/ussuri
Review: https://review.opendev.org/c/openstack/manila/+/791793

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/victoria
Review: https://review.opendev.org/c/openstack/manila/+/792290

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/792290
Committed: https://opendev.org/openstack/manila/commit/fa9ac6d78216bcddda36f60bb36476da91b2e521
Submitter: "Zuul (22348)"
Branch: stable/victoria

commit fa9ac6d78216bcddda36f60bb36476da91b2e521
Author: Tom Barron <email address hidden>
Date: Wed Apr 21 09:38:33 2021 -0400

    Fix api error message for snapshot creation failure

    when the source share has ``snapshot_support`` False.

    The message said that the back end lacks snapshot support but this
    is not necessarily the case.

    Closes-bug: #1925342
    Change-Id: I09a83b63528c0988f3601dfd07ad6972165cb855
    (cherry picked from commit be29805859f0e759cfd96b5e1ef0afbd1d16f3c0)
    (cherry picked from commit fb5a4f936d6ecf7435005f72ef8d7068cf75f65e)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/train
Review: https://review.opendev.org/c/openstack/manila/+/794060

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/791793
Committed: https://opendev.org/openstack/manila/commit/4fab48de0f7d15e89270d360fd3dbe13a102e093
Submitter: "Zuul (22348)"
Branch: stable/ussuri

commit 4fab48de0f7d15e89270d360fd3dbe13a102e093
Author: Tom Barron <email address hidden>
Date: Wed Apr 21 09:38:33 2021 -0400

    Fix api error message for snapshot creation failure

    when the source share has ``snapshot_support`` False.

    The message said that the back end lacks snapshot support but this
    is not necessarily the case.

    Closes-bug: #1925342
    Change-Id: I09a83b63528c0988f3601dfd07ad6972165cb855
    (cherry picked from commit be29805859f0e759cfd96b5e1ef0afbd1d16f3c0)
    (cherry picked from commit fb5a4f936d6ecf7435005f72ef8d7068cf75f65e)
    (cherry picked from commit fa9ac6d78216bcddda36f60bb36476da91b2e521)

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/794060
Committed: https://opendev.org/openstack/manila/commit/42e8210fc9b89fec8400c477ed482a5f83101bc8
Submitter: "Zuul (22348)"
Branch: stable/train

commit 42e8210fc9b89fec8400c477ed482a5f83101bc8
Author: Tom Barron <email address hidden>
Date: Wed Apr 21 09:38:33 2021 -0400

    Fix api error message for snapshot creation failure

    when the source share has ``snapshot_support`` False.

    The message said that the back end lacks snapshot support but this
    is not necessarily the case.

    Closes-bug: #1925342
    Change-Id: I09a83b63528c0988f3601dfd07ad6972165cb855
    (cherry picked from commit be29805859f0e759cfd96b5e1ef0afbd1d16f3c0)
    (cherry picked from commit fb5a4f936d6ecf7435005f72ef8d7068cf75f65e)
    (cherry picked from commit fa9ac6d78216bcddda36f60bb36476da91b2e521)
    (cherry picked from commit 4fab48de0f7d15e89270d360fd3dbe13a102e093)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila 10.1.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila 13.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila 12.1.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila 11.1.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila train-eol release.