Revert split tests

[Swatinem]

Now that the testsuite does not use mostly the slow TransactionTestCase, but the faster TestCase, it should execute considerably faster.

Hopefully fast enough that we don’t need to split the testsuite anymore, so lets try :-)

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Pretty much reverts #1144

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.86%. Comparing base (786d94a) to head (935eeb1).
Report is 2 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1213   +/-   ##
=======================================
  Coverage   95.86%   95.86%           
=======================================
  Files         493      493           
  Lines       16871    16871           
=======================================
  Hits        16174    16174           
  Misses        697      697           

Flag	Coverage Δ
unit	95.86% <ø> (ø)

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Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

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