tests/test_tracking.py: Add missing attribute-based search test after set_tag

[coderabbitai]

Background

In tests/test_tracking.py, there is a placeholder for a missing test:

# TODO: Test attribute-based search after set_tag

(Line 2094, inside a search/filter runs test.)

Task

Implement the attribute-based search assertion following set_tag to ensure that runs can be found via tag-based filter expressions after tagging operations.

References

• PR: Dependencies: Bump mlflow from 2.14.1 to 2.22.4 #254
• File: tests/test_tracking.py, line 2094

/cc @amotl