Identify Guest Agent connection error by the ordinal instead of message (KBOSS)

[GaOrtiga]

Description

When a backup fails because connection with the VM's guest agent failed, the VM remains consistent, therefore, there is no need to place it in the BackupError state. This validation, however is done by verifying the error message sent by Libvirt, which can be different on older versions. It also does not cover every case of Guest Agent connection failures, as Libvirt's code contains multiple places where this error is thrown, with different messages.

This PR changes this validation to use the errors # (ordinal) instead of the message, to avoid these issues.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• Build/CI
• Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

I disabled the Guest Agent on the VM and tried creating a backup, and verified that the backup failed but the VM was no placed in the BackupError state.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 19.65%. Comparing base (4f11707) to head (4a4dd5d).

Files with missing lines	Patch %	Lines
...ervisor/kvm/resource/LibvirtComputingResource.java	50.00%	1 Missing ⚠️
.../wrapper/LibvirtValidateKbossVmCommandWrapper.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #13789      +/-   ##
============================================
- Coverage     19.65%   19.65%   -0.01%     
+ Complexity    19792    19791       -1     
============================================
  Files          6368     6368              
  Lines        574881   574882       +1     
  Branches      70351    70351              
============================================
- Hits         112970   112969       -1     
- Misses       449639   449641       +2     
  Partials      12272    12272              

Flag	Coverage Δ
uitests	3.41% <ø> (ø)
unittests	20.92% <33.33%> (-0.01%)	⬇️

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