kvm: do not delete system bridges and VLAN interfaces

[winterhazel]

Description

There are cases in which operators may want to manually create a bridge following the same naming convention used by the KVM agent (br<if>-<vid>) and configure it as a zone's traffic label, so that it can be also introduced as a guest network, for instance.

However, when the last vif from this guest network is unplugged, the KVM agent always deletes the bridge and its parent VLAN interface, even when the bridge is still in use outside the platform.

This change propagates the network labels of a zone's physical networks to the KVM agents, and makes them avoid cleaning up these bridges.

Fixes #14228.

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

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Tests are still pending.

[winterhazel]

@blueorangutan package

[blueorangutan]

@winterhazel 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

❌ Patch coverage is 6.49351% with 72 lines in your changes missing coverage. Please review.
✅ Project coverage is 18.02%. Comparing base (2974af8) to head (444f332).

Files with missing lines	Patch %	Lines
.../com/cloud/network/dao/PhysicalNetworkDaoImpl.java	4.00%	24 Missing ⚠️
...java/com/cloud/agent/manager/AgentManagerImpl.java	0.00%	18 Missing ⚠️
...ervisor/kvm/resource/LibvirtComputingResource.java	5.55%	17 Missing ⚠️
...ain/java/com/cloud/network/NetworkServiceImpl.java	0.00%	9 Missing ⚠️
...cloud/hypervisor/kvm/resource/BridgeVifDriver.java	42.85%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               4.22   #14324      +/-   ##
============================================
- Coverage     18.02%   18.02%   -0.01%     
- Complexity    16250    16251       +1     
============================================
  Files          5936     5936              
  Lines        535823   535898      +75     
  Branches      65612    65623      +11     
============================================
- Hits          96582    96573       -9     
- Misses       428242   428326      +84     
  Partials      10999    10999              

Flag	Coverage Δ
uitests	4.04% <ø> (ø)
unittests	19.09% <6.49%> (-0.01%)	⬇️

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[blueorangutan]

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✔️ debian ✔️ suse15. SL-JID 19429