Have a regular QA database cleanup

[jf-x-dev]

If test runs crash or get cancelled halfway through, the following can occur:

• Organisation doesn't get reset -> sessions, children etc remain in the database
• Organisation doesn't get deleted -> organisation remains in the database

Over time this data will build up in the database and cause us problems.

We should have a regular cleanup. At the moment, it is probably fine to manually clean up the database when problems start to happen. But if more tests are running more often, we should consider a daily/weekly cleanup.

[jf-x-dev]

A temporary fix was implemented in #407 to prevent organisation name clashes. If enough organisations build up, we could still run into problems.

[jf-x-dev]

Currently this is done manually every few days to prevent buildup of patients/teams. I'm also spending some time ensuring that tests properly clean up after being run.