test: add statistics verification to obj_pmalloc_mt test

[grom72]

Enable statistics in pmalloc mt tests. Extend diagnostic of some tests like pmalloc, prealloc result verification.

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This change is 

[codecov[bot]]

Codecov Report

Merging #5566 (e32965e) into master (7c189da) will increase coverage by 2.02%. The diff coverage is n/a.

:exclamation: Current head e32965e differs from pull request most recent head b8ed133. Consider uploading reports for the commit b8ed133 to get more accurate results

@@            Coverage Diff             @@
##           master    #5566      +/-   ##
==========================================
+ Coverage   72.25%   74.28%   +2.02%     
==========================================
  Files         145      145              
  Lines       22633    22131     -502     
  Branches     3771     3704      -67     
==========================================
+ Hits        16353    16439      +86     
+ Misses       6280     5692     -588