Downgrade EQProp-ColumnKnowledge soft_assert

[ggevay]

The soft_assert_or_log that signals when ColumnKnowledge does work after EquivalencePropagation has been unexpectedly happening a lot in CI. We have enough examples to start fixing the issue, and we don't want to keep CI flaky while we do so. Therefore, this PR downgrades this assert to just a tracing::error!. This way, it won't fail CI, but it will still emit a Sentry error when it happens on staging or production.

Additionally, the PR also:

• Includes the dataflow's ID in the error msg.
• Fixes plan tracing, so that we can separately observe the result of EQProp before CK happens.

Motivation

Tips for reviewer

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).
• If this PR includes major user-facing behavior changes, I have pinged the relevant PM to schedule a changelog post.

[def-]

Thanks, I removed the two ignored tests, good for me if they are green now: https://buildkite.com/materialize/nightly/builds/10649 Edit: Green

[ggevay]

Thank you! Merging.