Remove CholeskyGrad Op

[sudarsan2k5]

Fixes #1098

This PR removes CholeskyGrad Op and all the tests related to it.

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[brandonwillard]

We have to squash these before/when we merge; otherwise, this looks good, thanks!

[codecov]

Codecov Report

Merging #1302 (bdb521b) into main (14c394d) will increase coverage by 0.05%.
The diff coverage is n/a.

❗ Current head bdb521b differs from pull request most recent head aed5f93. Consider uploading reports for the commit aed5f93 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1302      +/-   ##
==========================================
+ Coverage   74.10%   74.15%   +0.05%     
==========================================
  Files         174      174              
  Lines       48673    48629      -44     
  Branches    10373    10364       -9     
==========================================
- Hits        36067    36061       -6     
+ Misses      10315    10277      -38     
  Partials     2291     2291              

Impacted Files	Coverage Δ
aesara/tensor/slinalg.py	95.40% <ø> (+11.00%)	⬆️

[rlouf]

I just rebased your changes on main, will merge if the tests pass. Thank you for contributing!