Allow MLE test to fail

[penelopeysm]

Closes #2744

[github-actions]

Turing.jl documentation for PR #2746 is available at:
https://TuringLang.github.io/Turing.jl/previews/PR2746/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.51%. Comparing base (1773cd8) to head (a903c3b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2746       +/-   ##
===========================================
+ Coverage   55.34%   86.51%   +31.17%     
===========================================
  Files          20       20               
  Lines        1254     1261        +7     
===========================================
+ Hits          694     1091      +397     
+ Misses        560      170      -390     

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