ROX-13692: create final snapshot for tenant db

[johannes94]

Description

This PR changes the central tenant DB deletion for RDS so that it always creates a final snapshot this is required in order to restore the tenant in case it has been deleted accidentally by a customer, an engineer or an error in the code.

Checklist (Definition of Done)

• Unit and integration tests added
• Added test description under Test manual
• Documentation added if necessary (i.e. changes to dev setup, test execution, ...)
• CI and all relevant tests are passing
• Add the ticket number to the PR title if available, i.e. ROX-12345: ...
• Discussed security and business related topics privately. Will move any security and business related topics that arise to private communication channel.
• Add secret to app-interface Vault or Secrets Manager if necessary

Test manual

Adding test case and running rds tests locally and in CI.

# To run tests locally run:
make db/teardown db/setup db/migrate
make ocm/setup OCM_OFFLINE_TOKEN=<ocm-offline-token> OCM_ENV=development
make verify lint binary test test/integration

[johannes94]

/retest

[kovayur]

Do we have any retention rules for the final snapshot?

[johannes94]

Do we have any retention rules for the final snapshot?

@kovayur This is an excellent point. I thought it would use the same retention period as automated Snapshots. But turns out "Final Snapshots" are "Manual Snapshots" in AWS terms which don't have a retention mechanism like "System Snapshots". So this means if we do final snapshots, we have to make sure to clean them up at some point.

What do you think about creating a scheduled GitHub Workflow to do this?