e2e: Capture controller and driver pod logs

[matschaffer-roblox]

Purpose of this PR

Adds pod log capturing (spark-operator controller and driver) at the end of e2e tests.

Proposed changes:

• writePodLogs helper function to write named pod logs
• writeControllerLogs helper function to write logs from all controller pods
• add calls to e2e tests are part of AfterEach blocks

Change Category

• Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality) (for e2e tests)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

I found this helpful in recent PR work to catch exit logs before the pods go away. Committing it back to see if other folks are interested.

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

Opening as a draft for feedback. This was useful for me so I'll probably use it again, but I'm happy to close it if the maintainers have another approach for this. I considered installing loki in my kind cluster, for example, but this seemed more straightforward.

I can make documentation updates after discussion with the project team.

[google-oss-prow]

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