compiler: Fixup MPI over Arrays + arguments overriding

[FabioLuporini]

Tests to be added; likely in PRO because it's the only place where we can meaningfully excite this code path

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.99%. Comparing base (63a3e29) to head (fc65aa3).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2697      +/-   ##
==========================================
+ Coverage   87.66%   91.99%   +4.32%     
==========================================
  Files         248      248              
  Lines       49387    49387              
  Branches     4355     4355              
==========================================
+ Hits        43295    45432    +2137     
+ Misses       5340     3240    -2100     
+ Partials      752      715      -37     

Flag	Coverage Δ
pytest-gpu-aomp-amdgpuX	72.39% <33.33%> (?)
pytest-gpu-nvc-nvidiaX	73.45% <33.33%> (?)

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