Fix regression in chunk deletion for openstack provider

[shreyas-s-rao]

What this PR does / why we need it:
This PR fixes a recent regression in chunk deletion behavior for Openstack Swift snapshots. Additionally, remove backward compatibility tests between v1 and v2 for garbage collection, since v1 is no longer supported. Support for v1 backup directory structure in other parts of the code should be gradually removed as well, but not in this PR, to avoid scope spill.

Which issue(s) this PR fixes:
Fixes #702

Special notes for your reviewer:
/cc @plkokanov
/invite @ishan16696 @anveshreddy18 @seshachalam-yv

Release note:

A regression in chunk deletion behavior for openstack provider has now been fixed.

[ishan16696]

unit tests failed:

Summarizing 3 Failures:
  [FAIL] Save, List, Fetch, Delete from mock snapstore When both v1 and v2 are present [It] When both v1 and v2 are present
  /tmp/build/bc4dbee3/pull-request-gardener.etcd-backup-restore-master-pr/pkg/snapstore/snapstore_test.go:217
  [FAIL] Save, List, Fetch, Delete from mock snapstore When Only v2 is present [It] When Only v2 is present
  /tmp/build/bc4dbee3/pull-request-gardener.etcd-backup-restore-master-pr/pkg/snapstore/snapstore_test.go:267
  [FAIL] Save, List, Fetch, Delete from mock snapstore When Only v1 is present [It] When Only v1 is present
  /tmp/build/bc4dbee3/pull-request-gardener.etcd-backup-restore-master-pr/pkg/snapstore/snapstore_test.go:165

Additionally, remove backward compatibility tests between v1 and v2 for garbage collection, since v1 is no longer supported. Support for v1 backup directory structure in other parts of the code should be gradually removed as well, but not in this PR, to avoid scope spill.

I would suggest let's address all of these in separate PR, let's keep this PR for bug fix, so that it become easy and quick to review. WDYT?

[ishan16696]

unit tests also failed locally

[AfterSuite]
/Users/I539698/Desktop/review/etcd-backup-restore/pkg/snapstore/snapstore_suite_test.go:43
time="2024-01-08T14:53:39+05:30" level=info msg="Shutting down test server..."
[AfterSuite] PASSED [0.000 seconds]
------------------------------

Summarizing 3 Failures:
  [FAIL] Save, List, Fetch, Delete from mock snapstore When Only v1 is present [It] When Only v1 is present
  /Users/I539698/Desktop/review/etcd-backup-restore/pkg/snapstore/snapstore_test.go:165
  [FAIL] Save, List, Fetch, Delete from mock snapstore When both v1 and v2 are present [It] When both v1 and v2 are present
  /Users/I539698/Desktop/review/etcd-backup-restore/pkg/snapstore/snapstore_test.go:217
  [FAIL] Save, List, Fetch, Delete from mock snapstore When Only v2 is present [It] When Only v2 is present
  /Users/I539698/Desktop/review/etcd-backup-restore/pkg/snapstore/snapstore_test.go:267

Ran 115 of 115 Specs in 3.519 seconds
FAIL! -- 112 Passed | 3 Failed | 0 Pending | 0 Skipped
--- FAIL: TestSnapstore (3.52s)
FAIL

Ginkgo ran 1 suite in 8.47315375s

Test Suite Failed

I would suggest you can fix them in a separate PR.

[gardener-robot]

@ishan16696, @anveshreddy18, @seshachalam-yv You have pull request review open invite, please check

[ishan16696]

few nits

[shreyas-s-rao]

@ishan16696 thanks for your review. Addressed them. PTAL

[anveshreddy18]

Thanks for the PR @shreyas-s-rao.
/lgtm

[ishan16696]

Thanks @shreyas-s-rao for quickly fixing this issue.
LGTM!!

[ishan16696]

Please cherry-pick to branch rel-v0.24