Enable unnecessary-lambda Pylint check

[lbianchi-lbl]

Summary/Motivation:

• unnecessary-lambda is a built-in Pylint check, that might help addressing some of the issues with lambdas described in Add Pylint Check for Lambda Functions #1240
• However, this only looks as cases where my_func = lambda x, y: my_other_func(x, y), i.e where one could just simply set my_func = my_other_func
• More to the point, it does nothing to detect and prevent other uses of lambda that cause most of the issues in Add Pylint Check for Lambda Functions #1240 (specifically, by definition, the closure scope gotchas only arise when the lambda has fewer arguments that the function being used)

Changes proposed in this PR:

• Enable unnecessary-lambda Pylint check

Legal Acknowledgement

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1. I agree my contributions are submitted under the license terms described in the LICENSE.txt file at the top level of this directory.
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6decc12) 77.43% compared to head (916d2cb) 77.43%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1315      +/-   ##
==========================================
- Coverage   77.43%   77.43%   -0.01%     
==========================================
  Files         390      390              
  Lines       63758    63758              
  Branches    11737    11737              
==========================================
- Hits        49373    49370       -3     
- Misses      11841    11845       +4     
+ Partials     2544     2543       -1     

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[ksbeattie]

LGTM