Temp fix for the race condition during the tests.

[michaelgsharp]

Temporarily fixes the race condition that seems to be happening during the tests by making the offending tests run sequentially.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (64523e8) 68.81% compared to head (0c790ee) 68.81%.
Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7021      +/-   ##
==========================================
- Coverage   68.81%   68.81%   -0.01%     
==========================================
  Files        1258     1258              
  Lines      250477   250672     +195     
  Branches    25576    25614      +38     
==========================================
+ Hits       172377   172488     +111     
- Misses      71473    71551      +78     
- Partials     6627     6633       +6     

Flag	Coverage Δ
Debug	68.81% <ø> (-0.01%)	⬇️
production	63.27% <ø> (-0.02%)	⬇️
test	88.44% <ø> (+<0.01%)	⬆️

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Files	Coverage Δ
test/Microsoft.ML.Tests/DatabaseLoaderTests.cs	94.41% <ø> (ø)
...osoft.ML.Tests/Transformers/WordEmbeddingsTests.cs	100.00% <ø> (ø)

... and 23 files with indirect coverage changes

[tarekgh]

Could you please open issue to track removing the serialization later? Thanls!