chore: Remove non-celery code owner monitoring code and docs

[rahulkanneri-2u]

Removes the non-celery code owner monitoring code, docs, and the new_relic_search script, since this functionality is 2U-specific and has already been replaced by plugin-based instrumentation. The celery task decorator (set_code_owner_attribute) and its shared helpers are intentionally left in place, since it is still in active use and its removal is tracked separately.

Description:

Removes CodeOwnerMonitoringMiddleware and its supporting non-celery utilities, tests, and docs, plus the new_relic_search.py script and its docs. This is a trimmed-down replacement for #547, which mixed in premature removal of utils.py (the still-in-use celery decorator, set_code_owner_attribute). This PR leaves utils.py, test_utils.py, and the celery-related ADRs untouched.

JIRA:

#469

Dependencies:

None.

Merge deadline:

None currently.

Installation instructions:

None.

Testing instructions:

None.

Reviewers:

• tag reviewer

Merge checklist:

• All reviewers approved
• CI build is green
• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Commits are squashed

Post merge:

• Create a tag
• Check new version is pushed to PyPi after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)

Author concerns:

List any concerns about this PR - inelegant
solutions, hacks, quick-and-dirty implementations, concerns about
migrations, etc.

[robrap]

I misspoke. We should not be making any breaking changes, so the middleware also should not be removed. (Removal of the script could be considered a breaking change, but I am not counting that, so that is fine to stay.)

If we do anything, the most important change would be to add a deprecation warning to any public api that would be removed (e.g. middleware, celery function, etc.). We would also update the changelog.

Note: we need to timebox or not do any changes here. Thanks.

[rahulkanneri-2u]

Closing without merging. Per review (#551 (review)).

CodeOwnerMonitoringMiddleware removal is a breaking change for downstream consumers and shouldn't ship without a
deprecation warning first. We're timeboxing this DEPR and not taking on the deprecation-warning work right now, so
deferring this cleanup rather than continuing to iterate. Tracked in #469.