Update AutoMLExperimentTests.cs to fix timeout error

[LittleLittleCloud]

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fix #6637
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[codecov]

Codecov Report

Merging #6638 (c79e9d0) into main (e30555c) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6638      +/-   ##
==========================================
- Coverage   68.53%   68.52%   -0.01%     
==========================================
  Files        1200     1200              
  Lines      250288   250288              
  Branches    26093    26093              
==========================================
- Hits       171524   171518       -6     
- Misses      71932    71935       +3     
- Partials     6832     6835       +3     

Flag	Coverage Δ
Debug	68.52% <100.00%> (-0.01%)	⬇️
production	63.00% <ø> (-0.01%)	⬇️
test	88.83% <100.00%> (ø)

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Impacted Files	Coverage Δ
...Microsoft.ML.AutoML.Tests/AutoMLExperimentTests.cs	88.34% <100.00%> (ø)

... and 4 files with indirect coverage changes