Running the test suite creates plugins which prevent running the test suite again

Description

When running the whole test suite via the Makefile, some tests create plugins which do not get deleted afterwards (due to recent changes in the git ignore file the are not in the persistence context anymore). This causes an issue when trying to run the whole test suite again.

Expected Behavior

make unit-test can be run consecutively without any further actions required.

Actual Behavior

Running make unit-test twice or more does not work correctly as described earlier. Clean up created plugins after running the tests.

Steps to Reproduce

1. Run make unit-test
2. Run the same command again