Branch rules: update toggle design and descriptions
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# Context
In https://gitlab.com/gitlab-org/gitlab/-/issues/391938#note_2086015740, a new toggle was added to the branch rules details page to allow users to synchronize forks.
The toggles take up space and the visual design approach could be improved.
# Proposal
Suggested changes:
* Integrate the toggles into a crud-like component
* Add helper text to the toggles with links to docs
[:art: Figma](https://www.figma.com/design/eq2nf3B8MhB9xKrC0VzbPf/branch/YmfjKSXtV0qrJmodVMfved/Repository?m=auto&node-id=4657-64283&t=gZutPiDxItt4v4pl-1)
| Current | Proposed |
|---------|----------|
|  |  |
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