Add config option 'reserved_share_extend_percentage'

[kiran pawar]

We want to introduce a 'reserved_share_extend_percentage' to allow a different value for reservation percentage for the share extend operation.

There are two use cases -
1) Under existing limit of 'reserved_share_percentage', we do not want user to create new share if limit is hit, but allow user to extend existing share.

2) With --force option, share extend will go through scheduler. This might move share to some other backend. We can possibly avoid --force option in case share extend allowed with lower value of `reserved_share_extend_percentage` against `reserved_share_percentage`.

[Vida Haririan (vhariria)]

For additional comments please refer to https://meetings.opendev.org/meetings/manila/2022/manila.2022-02-24-15.02.log.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/manila/+/832843

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/832843
Committed: https://opendev.org/openstack/manila/commit/6431b86f19d09e1076e191d0ea5e794cc95bfac6
Submitter: "Zuul (22348)"
Branch: master

commit 6431b86f19d09e1076e191d0ea5e794cc95bfac6
Author: Manish Honap <email address hidden>
Date: Wed Mar 9 01:32:25 2022 +0530

    Add config option reserved_share_extend_percentage

    'reserved_share_extend_percentage' backend config option allows Manila
    to consider different reservation percentage for share extend
    operation. With this option, under existing limit of
    'reserved_share_percentage', we do not want user to create new share if
    limit is hit, but allow user to extend existing share.

    DocImpact

    Closes-Bug: #1961087
    Change-Id: I000a7f530569ff80495b1df62a91981dc5865023

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila 15.0.0.0rc1 release candidate.