Jest Open Handles

[Lindeneg]

Apparently the cleanup is not done correctly in the live-server tests, even though the server is shutdown after each test and a global teardown that kills the test process is performed.

For now, a hacky solution is implemented by running Jest with --forceExit and --runInBand, both of which are discouraged.

It seems to be Jest having issues because node doesn't emit a destroy event for the TLSWRAP hook. However, supertest does seem to be able to handle this and thus a permanent fix could be to refactor all live-server tests to use supertest.