Address group-level protected branches redirection to Branch rules

Context

&12494 (comment 2317268709) &17598

Now that Branch rules have been released, having the Repository Settings > Protected branches section may be unnecessary and even confusing to users.

We are adding messaging in #523300 (comment 2455162300) to redirect users from Protected branches to Branch rules. However, the Protected branches section still exists on the group level.

Design questions:

• How should we handle redirecting users on a group level from the Protected branches section to the Branch rules section?
• What are the risks associated with this? Are there any breaking changes?

[Draft] Design proposal

TBD @alyssatrinh