Revert split tests

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 :-)

Author: Swatinem

.github/workflows/ci.yml

@@ -40,7 +40,7 @@ jobs:
   test:
     name: Test
     needs: [build]
-    uses: codecov/gha-workflows/.github/workflows/run-tests-split[email protected]
+    uses: codecov/gha-workflows/.github/workflows/[email protected]
     secrets: inherit
     with:
       run_integration: false