[testing] Write functional/integration tests

[kinow]

Our functional and integration tests have been disabled for a long time. We have been trying to add more unit tests, but there is only so much you can unit test with mocks until you start writing tests for your mocks, and not for your code. Certain scenarios can only be covered by integration or functional tests.

This issue is a placeholder to gather the tests as we find scenarios like this when working on issues and merge requests.

• tests for exit code 0, including if a signal is raised by the user https://earth.bsc.es/gitlab/es/autosubmit/-/merge_requests/390#note_240766
• tests for platforms https://earth.bsc.es/gitlab/es/autosubmit/-/issues/977
• tests for each subcommand executed
  • verify if the lockable subcommands are really locked - https://earth.bsc.es/gitlab/es/autosubmit/-/merge_requests/512