backend: default persona persisted even after persona is removed

[chirag-madlani]

Affected module
Does it impact the UI, backend or Ingestion Framework?
backend

Describe the bug
A clear and concise description of what the bug is.

defaultPersona value is being persisted even after removing persona from that user

To Reproduce

1. Create a User and assign persona to it
2. Assign that persona as default
3. Remove it from Persona list
4. Backed still has that persona as defaultPersona

Screenshots or steps to reproduce

Expected behavior
A clear and concise description of what you expected to happen.

If persona is no longer with User, backend should remove it from DefaultPersona too

Version:

• OS: [e.g. iOS]
• Python version:
• OpenMetadata version: 1.5.4
• OpenMetadata Ingestion package version: [e.g. openmetadata-ingestion[docker]==XYZ]

Additional context
Add any other context about the problem here.