Show pull mirror settings in UI
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### Problem to solve
When a [pull mirror](https://docs.gitlab.com/ee/user/project/repository/repository_mirroring.html#pulling-from-a-remote-repository-starter) is set up (either by adding mirroring, or by setting it up to provide CI to an external repository) three settings might have been selected:
* `Overwrite diverged branches.`
* `Trigger pipelines for mirror updates.`
* `Only mirror protected branches.`
Once set up, the state of these three options doesn't appear to be surfaced in the UI. 'Mirroring Repositories' in Settings -> Repository would seem to be the logical place.

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### Intended users
* [Sasha (Software Developer)](https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/#sasha-software-developer)
* [Devon (DevOps Engineer)](https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/#devon-devops-engineer)
* [Sidney (Systems Administrator)](https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/#sidney-systems-administrator)
### Further details
For a lot of users, the only way to know for sure is to delete the sync config and set it up again.
And then maintain separate internal documentation about what it's been set to.
### Proposal
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### Permissions and Security
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### Documentation
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### Availability & Testing
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* Integration test changes
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### Is this a cross-stage feature?
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### Links / references
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