Address group-level protected branches redirection to Branch rules
# Context
https://gitlab.com/groups/gitlab-org/-/epics/12494#note_2317268709 https://gitlab.com/groups/gitlab-org/-/epics/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 UI in https://gitlab.com/gitlab-org/gitlab/-/work_items/576754 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?
# Proposal
See https://gitlab.com/gitlab-org/gitlab/-/issues/537081#note_2612488982, https://gitlab.com/gitlab-org/gitlab/-/issues/537081#note_3114193500:
* Changed both the group and project-level descriptions when possible to:
* `Define push, merge, and approval rules for each branch. `[`What are branch rules?`](https://docs.gitlab.com/user/project/repository/branches/branch_rules/)
* When the Protected Branches project-level redirect is implemented https://gitlab.com/gitlab-org/gitlab/-/work_items/576754, add a banner to the group-level alerting users that the `Protected branches` section has been renamed to `Branch rules`.
* Change the name of the Group-level `Protected Branches` section to `Branch rules`, and update the section description text.
While it would be a better user experience to create a `Branch rules` section on the Group-level with the same capabilities as the Project-level Branch rules https://gitlab.com/gitlab-org/gitlab/-/issues/537081#note_2528024447, this was evaluated to be a significant amount of development work per https://gitlab.com/gitlab-org/gitlab/-/issues/537081#note_2570566226. Until https://gitlab.com/groups/gitlab-org/-/work_items/20360 is implemented, this is the interim solution.
### Groups
<table>
<tr>
<th>Current (Group)</th>
<th>Proposed (Group)</th>
</tr>
<tr>
<td>
{width="900" height="497"}
**Protected branches**
Keep stable branches secure and force developers to use merge requests. [What are protected branches?](https://gitlab.com/help/user/project/repository/branches/protected.md)
</td>
<td>
{width=664 height=600}
Banner:
* Protected branches is now Branch rules. Your existing settings are unchanged.
Section text:
* **Branch rules**
* Define push, merge, and approval rules for each branch. [What are branch rules?](https://docs.gitlab.com/user/project/repository/branches/branch_rules/)
</td>
</tr>
</table>
### Projects
<table>
<tr>
<th>Current (Project)</th>
<th>Proposed (Project)</th>
</tr>
<tr>
<td>
{width="785" height="600"}
**Branch rules**
Define rules for who can push, merge, and the required approvals for each branch. [Leave feedback.](https://gitlab.com/gitlab-org/gitlab/-/issues/388149)
</td>
<td>
{width="900" height="596"}
**Branch rules**
Define push, merge, and approval rules for each branch. [What are branch rules?](https://docs.gitlab.com/user/project/repository/branches/branch_rules/)
</td>
</tr>
</table>
###
issue