Deprecate Kustomize manifests

[ChenYi015]

Purpose of this PR

• Deprecate Kustomize manifests since it is not maintained for a long time.
• The alternative and recommended way is to use Helm to manage Spark operator releases.

Proposed changes:

• Remove Kustomize manifests and stop generating it.
• Generate CRDs into charts/spark-operator-chart/crds instead of config/crd/bases.
• Remove Makefile targets detect-crds-drift and update-crd.
• Update integration test workflow.

Change Category

• Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

Checklist

• I have conducted a self-review of my own code.
• I have updated documentation accordingly.
• I have added tests that prove my changes are effective or that my feature works.
• Existing unit tests pass locally with my changes.

Additional Notes

[google-oss-prow]

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[nabuskey]

There might be people using our repo as their Kustomize base. I'd say we put up a deprecation notice first in the next release, then remove them after the release.

[ChenYi015]

Make sense. Will announuce the deprecation of Kutomize manifests in the next release.
/hold