Glance muti store support broken since Rocky

[Bjoern]

Glance updated the multi store configuration in Rocky and since then the support seems broken.
For example:

Related Options:
default_store

 Warning

This option is deprecated for removal since Rocky. Its value may be silently ignored in the future.

Reason
This option is deprecated against new config option enabled_backends which helps to configure multiple backend stores of different schemes. This option is scheduled for removal in the U development cycle.

along with new configuration options which needs to be implemented.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/718513

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/718513
Committed: https://git.openstack.org/cgit/openstack/openstack-ansible-os_glance/commit/?id=22c9bc06a9f0449aa120bc2b9a7ffaad4b6e16a5
Submitter: Zuul
Branch: master

commit 22c9bc06a9f0449aa120bc2b9a7ffaad4b6e16a5
Author: Dmitriy Rabotyagov <email address hidden>
Date: Wed Apr 8 19:27:24 2020 +0300

    Update glance_store variables

    Some variables were deprecated in rocky and marked for removal in Ussuri
    We do replace them not to have things broken afterwards.

    Change-Id: I75d2e3631b0dfebb72efd946fd61252bb9b766b0
    Related-Bug: #1846052

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/722854

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/722854
Committed: https://git.openstack.org/cgit/openstack/openstack-ansible-os_glance/commit/?id=6495419a9f6b617428e6dd25eb3102309fdcd146
Submitter: Zuul
Branch: master

commit 6495419a9f6b617428e6dd25eb3102309fdcd146
Author: Dmitriy Rabotyagov <email address hidden>
Date: Fri Apr 24 18:30:25 2020 +0300

    Fix glance stores

    Patch [1] brought a bug to glance configuration due to which glance-api
    wasn't brought up. The issue was in the multiple backends issue which
    require each backend to be specified in their own section.[2]

    [1] https://review.opendev.org/#/c/718513/2
    [2] https://docs.openstack.org/glance/train/admin/multistores.html

    Change-Id: If0c06a5b727c4f0c3e5abf36bd6d2434f09b5857
    Related-Bug: #1846052