valgrind tests

[galabovaa]

• IPX test fix for valgrind
• fix resetGlobalScheduler warning I introduced in TestPresolve
• add Github Action for valgrind of unit and instance tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.20%. Comparing base (22f165c) to head (14e7a68).
Report is 22 commits behind head on latest.

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #2295      +/-   ##
==========================================
- Coverage   79.21%   79.20%   -0.01%     
==========================================
  Files         343      343              
  Lines       83857    83866       +9     
==========================================
+ Hits        66427    66429       +2     
- Misses      17430    17437       +7     

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[galabovaa]

This is generally ready to merge. Just test updates, the failing one is valgrind of the two unit tests, one of which is already fixed on your other branch