tests/frontend/workspace.py: Remove redundant and pointless tests
The following tests all test core functionalities for which the plugin type cannot possibly have any effects on the result, because none of the tested functionalities in these tests are delegated to plugins in anyway:
- test_open_track
- test_open_force
- test_open_force_open
- test_open_force_different_workspace
- test_close
- test_inconsitent_pipeline_message
Reduced these tests to only test with the git plugin, instead of redundantly running these tests against every plugin.