Update placement.group when instance is running

[vosdev]

Please confirm

• I have searched existing issues to check if an issue already exists for my feature request.

Is your feature request related to a problem? Please describe.

I'm always frustrated when..

Key "placement.group" cannot be updated when VM is running

Describe the solution you'd like

Allow us to update this value. Unless I am mistaken, the value doesn't have any modifying effect on running instances.

Describe alternatives you've considered

Shutting down my instances to modify this value

Additional context

No response