Remove the use of KeyVault

[K-S-Bakken]

Describe the improvement you would like to see
Remove the use of KeyVault in Flotilla.
Need to change the builder configuration, see picture. Also appsettings.

How will this change existing functionality?
Makes the use of KeyVault optional, not required.

How will this improvement affect the current Threat Model?
Improved handling of secrets.

[K-S-Bakken]

Is dependent on #2713

[K-S-Bakken]

Waiting for the integration tests to be back up and running to verify this

[github-actions]

This issue has been automatically marked as stale due to inactivity.