ci: Fix unit tests OOM

[mateczagany]

Tune memory for Maven and surefire explicitly.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 13.11%. Comparing base (ec97eda) to head (af9dc9d).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #2004   +/-   ##
=========================================
  Coverage     13.11%   13.11%           
  Complexity      780      780           
=========================================
  Files           592      592           
  Lines         16849    16849           
  Branches       1971     1971           
=========================================
  Hits           2210     2210           
  Misses        14436    14436           
  Partials        203      203           

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