Support removing ResourceEventHandler for informers

[csviri]

Description

Fixes #6501

• feat: make it possible to remove event handler from informers

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift

[csviri]

fixes #6501

[sonarqubecloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[csviri]

@manusa @shawkins the build fail seems to be unrelated. Coverage is 0% since the tests are in different module, pls let me know if I need to polish something on this. thank you!

[manusa]

LGTM, thx!

[shawkins]

LGTM, thanks @csviri