Use findOrCreate to handle retrying failed setup

[Pezmc]

Description

If setup fails at any step, the database can be left in a half setup state.

When the user tries setup a second time, it fails with a database constraint about duplicate entries.
Using findOrCreate means if the record already exists, it won't try to be recreated.

Related Issue(s)

Checklist

• I have read the contribution guidelines
• [-] Suitable unit/system level tests have been added and they pass - Not sure how to test setup reliably...
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on flowforge/helm to update ConfigMap Template
  • Issue/PR raised on flowforge/CloudProject to update values for Staging/Production

Labels

• Backport needed? -> add the backport label
• Includes a DB migration? -> add the area:migration label