Fix GPU test CI condition to run nightly or on demand

[kevalmorabia97]

• Fix GPU test nightly run (previously was skipped in nightly)
• Allow all workflows to be run on-demand from Actions tab
• Skip mcore dataset unit test on windows
• Use L4 for PR test and H100 for nightly / on-demand tests for better runner util and less queuing

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.83%. Comparing base (b38dfb6) to head (9af27b1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #269      +/-   ##
==========================================
- Coverage   73.84%   73.83%   -0.01%     
==========================================
  Files         175      175              
  Lines       17326    17326              
==========================================
- Hits        12794    12793       -1     
- Misses       4532     4533       +1     

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