Fix flaky test

[fractalwrench]

Goal

EmbraceCacheServiceConcurrentAccessTest started failing sporadically because the TestPlatformSerializer did not override all serializer functions. The serialization code was recently changed to use a different function signature & therefore execution wasn't paused, resulting in a race condition that failed some assertions.

I ran this test case ~10 times locally to verify it now passes & also avoided inheritance by delegation to ensure this problem is more obvious if it ever happens in future.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.71%. Comparing base (2541327) to head (9a2bcdc).
Report is 1 commits behind head on integration/v2-migration.

Additional details and impacted files

@@                     Coverage Diff                      @@
##           integration/v2-migration     #968      +/-   ##
============================================================
+ Coverage                     79.69%   79.71%   +0.01%     
============================================================
  Files                           407      407              
  Lines                         10826    10826              
  Branches                       1720     1720              
============================================================
+ Hits                           8628     8630       +2     
+ Misses                         1419     1417       -2     
  Partials                        779      779              

see 1 file with indirect coverage changes

[bidetofevil]

Ugh. Of course! Thanks for fixing this!