fix #3101 making isWatching better reflect health

[shawkins]

Description

Based upon trying to close out #3101 it seems better to refine the flag behavior so that it will be better as health checks. So now if a non-http gone exception is provided we'll also report running = false. And in the http gone case we won't report anything as wrong until something fails with the re-list/watch.

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

[centos-ci]

Can one of the admins verify this patch?

[rohanKanojia]

Our sharedindexinformer API has been refactored a lot since past two releases. I think we should review our existing CHEATSHEET doc[0] to see if it's up to date with latest changes. I think we can document these health check methods there too

[0] https://github.com/fabric8io/kubernetes-client/blob/master/doc/CHEATSHEET.md#sharedinformers

[shawkins]

@rohanKanojia updated the cheatsheet as well.

[sonarqubecloud]

SonarCloud Quality Gate failed.

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

75.0% Coverage
0.0% Duplication

[manusa]

LGTM, thx!