Silence deprecation warnings emitted by Pyomo tests

[jsiirola]

Fixes # .

Summary/Motivation:

This PR silences a number of deprecation warnings that are emitted by the Pyomo test harness.

Changes proposed in this PR:

• Remove outdates references to cloning expressions from Pyomo online documentation
• Update numpy.math references in DAE (this was also included in Replace deprecated numpy.math alias with standard library math module #3074)
• Update stats..gaussian_kde references in parmest
• Rename the test_solver_cases utility function so pytest does not attempt to run it as a test

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (13a3234) 88.09% compared to head (06eef0f) 88.09%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3076   +/-   ##
=======================================
  Coverage   88.09%   88.09%           
=======================================
  Files         774      774           
  Lines       91538    91538           
=======================================
  Hits        80637    80637           
  Misses      10901    10901           

Flag	Coverage Δ
linux	85.45% <100.00%> (ø)
osx	75.47% <0.00%> (ø)
other	85.63% <100.00%> (ø)
win	82.79% <100.00%> (ø)

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[mrmundt]

Do you want to merge #3074 first?

[jsiirola]

Do you want to merge #3074 first?

Yes.