Fix NPE in NASBackupProvider when no running KVM host is available

[jmsperu]

Rebased onto 4.22 as requested (previously #12680).

ResourceManager.findOneRandomRunningHostByHypervisor() can return null when no KVM host in the zone has status=Up (e.g. during management server startup, brief agent disconnections, or host state transitions).

NASBackupProvider.syncBackupStorageStats() and deleteBackup() call host.getId() without a null check, causing a NullPointerException that crashes the entire BackupSyncTask background job every sync interval.

This adds null checks in both methods:

• syncBackupStorageStats: log a warning and return early
• deleteBackup: throw CloudRuntimeException with a descriptive message

[DaanHoogland]

@blueorangutan package

[blueorangutan]

@DaanHoogland a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 3.70%. Comparing base (27bce46) to head (30b707c).

❗ There is a different number of reports uploaded between BASE (27bce46) and HEAD (30b707c). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (27bce46)	HEAD (30b707c)
unittests	1	0

Additional details and impacted files

@@              Coverage Diff              @@
##               4.22   #12805       +/-   ##
=============================================
- Coverage     17.61%    3.70%   -13.91%     
=============================================
  Files          5917      448     -5469     
  Lines        531415    38028   -493387     
  Branches      64973     7036    -57937     
=============================================
- Hits          93588     1409    -92179     
+ Misses       427271    36432   -390839     
+ Partials      10556      187    -10369     

Flag	Coverage Δ
uitests	3.70% <ø> (ø)
unittests	?

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[blueorangutan]

Packaging result [SF]: ✖️ el8 ✖️ el9 ✖️ debian ✖️ suse15. SL-JID 17121

[DaanHoogland]

@jmsperu , probably due to the rebase:

20:18:12 [ERROR] /jenkins/workspace/acs-centos8-pkg-builder/dist/rpmbuild/BUILD/cloudstack-4.22.1.0-SNAPSHOT/plugins/backup/nas/src/main/java/org/apache/cloudstack/backup/NASBackupProvider.java:[558,12] error: cannot find symbol
20:18:12   symbol:   variable CollectionUtils
20:18:12   location: class NASBackupProvider

seems an import is missing.

[jmsperu]

Good catch @DaanHoogland, the CollectionUtils import was dropped during the rebase. Fixed now — should build cleanly.