Add support for marking and skipping slow tests, temporarily mark pydantic tests as slow

[pstjohn]

Description

These pydantic CLI tests are currently taking an inordinate amount of time to run. This PR adds support for using pytest.mark.slow to flag tests not to run during pre-merge testing, but will still be run during nightly tests.

Also adds some cleanup to the azure runner test suite to remove the docker container from the GPU runner since these are not ephemeral workers, and updates the cache mounting location for the container job to re-use downloads.

See https://nvidia.slack.com/archives/C074Z808N05/p1736460988702949
https://jirasw.nvidia.com/browse/BIONEMO-553

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactor
• Documentation update
• Other (please describe):

CI Pipeline Configuration

Configure CI behavior by checking relevant boxes below. This will automatically apply labels.

• SKIP_CI - Skip all continuous integration tests
• INCLUDE_NOTEBOOKS_TESTS - Execute notebook validation tests in pytest

Note

By default, the notebooks validation tests are skipped unless explicitly enabled.

Usage

TODO: Add code snippet

Pre-submit Checklist

• I have tested these changes locally
• I have updated the documentation accordingly
• I have added/updated tests as needed
• All existing tests pass successfully

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.78%. Comparing base (c691df2) to head (be176e9).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #589      +/-   ##
==========================================
+ Coverage   87.73%   88.78%   +1.04%     
==========================================
  Files          89       81       -8     
  Lines        5758     5027     -731     
==========================================
- Hits         5052     4463     -589     
+ Misses        706      564     -142     

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