Remaining issues for simplified team plans

[jankeromnes]

Bug description

Remaining small problems before the new Team Billing can be un-hidden, to finish #7759 :

• Staging does not handle the new Chargebee webhooks properly?

Potentially relevant error from the payment pod:

QueryFailedError: ER_DATA_TOO_LONG: Data too long for column 'userId' at row 1

• Did pro-ration on team join break?
• Polish UI (especially in Dark theme) [Design] Team Plans v2 #8352
• Un-hide the new Team Billing

Steps to reproduce

N/A

Workspace affected

No response

Expected behavior

No response

Example repository

No response

Anything else?

No response