Refactor some service tests and make them not require db

This refactors service tests in a few different ways:

 - Remove unnecessary calls
 - Make tests test what they say instead of something that other tests
   already cover (make TestLauncher into something else than testing
   what test_service_random_port already does)
 - Make them not require db

Change-Id: Ic2dfbc0d2ccf7a1f71929b78d7c7d784a2f8b7f5