feat: add subscriber k8s fuzz test

[inpyu]

Proposed changes

add fuzz test in /chaoscenter/graphql/server/pkg/k8s

Types of changes

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• New feature (non-breaking change which adds functionality)
• Bugfix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices applies)

Checklist

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• I have read the CONTRIBUTING doc
• I have signed the commit for DCO to be passed.
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

Dependency

• Please add the links to the dependent PR need to be merged before this (if any).

Special notes for your reviewer:

[namkyu1999]

Can you check a build pipeline? @inpyu

[namkyu1999]

Good first attempts. We need to use fake client for these cases because this pkg depends on kubeclient.

[namkyu1999]

Suggested change

	if KubeConfig == nil {
	return rest.InClusterConfig()
	}
	if *KubeConfig == "" {
	return rest.InClusterConfig()
	}
	if *KubeConfig == "" || KubeConfig == nil {
	return rest.InClusterConfig()
	}

[namkyu1999]

can you keep this line?