[Tracking] Charm missing ussuri and focal support

Fix proposed to branch: master
Review: https://review.opendev.org/729932

This work is already completed.

Change abandoned by Aurelien Lourot (<email address hidden>) on branch: master
Review: https://review.opendev.org/729932
Reason: Superseded by https://review.opendev.org/#/c/739929/ . Also the same test failure happens there

Reviewed: https://review.opendev.org/730377
Committed: https://git.openstack.org/cgit/openstack/charm-cinder-backup-swift-proxy/commit/?id=4755bf6b74902baa1fa56e707e056ad2d1f594e8
Submitter: Zuul
Branch: master

commit 4755bf6b74902baa1fa56e707e056ad2d1f594e8
Author: Alex Kavanagh <email address hidden>
Date: Fri May 22 17:52:46 2020 +0100

    Add focal and ussuri test bundles to the charm

    Note: this will fail due to Bug: #1865754 which affects os-brick and
    Ceph Octopus in focal. This can be landed or the focal-ussuri bundle
    disabled to a dev bundle whilst waiting on the fix.

    Change-Id: I45ef775ad177e52b2ac6eaccd196c9518d25c03c
    Closes-Bug: #1879684
    Related-Bug: #1865754

Reviewed: https://review.opendev.org/736275
Committed: https://git.openstack.org/cgit/openstack/charm-manila-generic/commit/?id=211a5dbae5877de41ebacbd7aa3f739989ba3cb4
Submitter: Zuul
Branch: master

commit 211a5dbae5877de41ebacbd7aa3f739989ba3cb4
Author: Alex Kavanagh <email address hidden>
Date: Wed Jun 17 16:46:37 2020 +0100

    Add bionic-ussuri and focal-ussuri test bundles

    Also switch the smoke bundle to focal-ussuri as that will be the LTS on
    focal.

    Change-Id: I91ae66a5903c23c663243dfd10270d04325e5e39
    Closes-Bug: #1879684

Reviewed: https://review.opendev.org/729932
Committed: https://git.openstack.org/cgit/openstack/charm-cinder-backup/commit/?id=a1dade70f95e6e0c5de66903b8bfabaf336ca373
Submitter: Zuul
Branch: master

commit a1dade70f95e6e0c5de66903b8bfabaf336ca373
Author: Alex Kavanagh <email address hidden>
Date: Thu May 21 12:49:18 2020 +0100

    Add focal and ussuri test bundles

    The focal-ussuri test is disabled for gate (it's in dev bundles) due to
    the upstream bug [1] in os-brick connecting to ceph-octopus in focal.
    Bug [2] is for tracking the issue against the charms.

    Related-Bug: #1865754 [1]
    Related-Bug: #1891626 [2]
    Closes-Bug: #1879684

    func-test-pr: https://github.com/openstack-charmers/zaza-openstack-tests/pull/390
    Change-Id: I64c4ef1d7f5c183b7f04e089e126eda52136d7fc