Fix errors with decomposed production with invalid cache entries

[isc-pbarton]

Closes #701

• Fix an error when there is a leftover entry in the Git items cache for the undecomposed production class
• Removes Add to / Remove From Source Control options from menu for decomposed production since they do nothing

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 41.29%. Comparing base (b29baf0) to head (3f6851e).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
cls/SourceControl/Git/Extension.cls	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #702      +/-   ##
==========================================
- Coverage   41.33%   41.29%   -0.05%     
==========================================
  Files          23       23              
  Lines        3174     3175       +1     
==========================================
- Hits         1312     1311       -1     
- Misses       1862     1864       +2     

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