Fix: Stripe out of sync when removing project

[Pezmc]

Description

Swallow Customer cus_M3Aypx6T6nn19k does not have a subscription with ID sub_1LL4c9J6VWAujNoL1CbsXuzb\ error from Stripe.

This means that if a subscription has been deleted in Stripe, it's still possible to delete the instance in FlowForge.

Related Issue(s)

Fixes #1837

Checklist

• I have read the contribution guidelines
• [-] Suitable unit/system level tests have been added and they pass
  • Unable to clearly add coverage
• [-] 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