fix: webhook fail to add lifecycle to Spark3 executor pods

[pvbouwel]

Before this fix if you have a Spark 3.x spec where the executor has a lifecycle then the webhook will fail to identify the correct container. As described in issue 2457

Purpose of this PR

Solve the bug as detailed in #2457 where spark3 executors are blocked if they have a lifecycle

Proposed changes:

• re-use code to identify the container in the pod

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 => Not applicable ?
• 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

[ChenYi015]

@pvbouwel Thank you for reporting the bug and raising a PR to fix it!
Please run make go-fmt to format the code to pass the CI check. By the way, we recommend using pod template feature to configure lifecycle of Spark pods since we are going to deprecate the webhook in the future.

[pvbouwel]

Pushed formatting. Thanks for the info; I will look into the pod template feature such that we can migrate our workflows early on

[ChenYi015]

/lgtm

[google-oss-prow]

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