storage/sink/kafka: prevent queue full by disabling buffering

[benesch]

Now that we're on librdkafka v2.4.0, we don't need to catch and retry QueueFull errors, but can instead disable the queue limit.

This commit is a combination of:

• Reverting the QueueFull workaround from storage: handle librdkafka queue saturation in sinks #24871
• Reapplying Petros's original implementation in storage: remove kafka producer limits in sinks #24784

Motivation

• This PR refactors existing code.

Checklist

• This PR has adequate test coverage / QA involvement has been duly considered. (trigger-ci for additional test/nightly runs)
• This PR has an associated up-to-date design doc, is a design doc (template), or is sufficiently small to not require a design.
• If this PR evolves an existing $T ⇔ Proto$T mapping (possibly in a backwards-incompatible way), then it is tagged with a T-proto label.
• If this PR will require changes to cloud orchestration or tests, there is a companion cloud PR to account for those changes that is tagged with the release-blocker label (example).
• This PR includes the following user-facing behavior changes:
  • n/a

[petrosagg]

Thank you! Good memory, I had forgotten about this workaround :D