When activating an external issue tracker, automatically de-activate all other ones
- Inside the project integration settings, when activating one external issue tracker, automatically de-activate all other external issue trackers.
- Note that this is fully independent of the internal GitLab issue tracker.
- In particular, "activating" means turning "on" that particular integration with the checkbox in the settings and persisting that flag. When that happens, all the other flags of all other issue trackers are automatically switched off.
- Need some UI to tell the user that is the case when this happens.
- We should not delete any settings in this scenario (in any of the issue tracker integration settings). So that this is minimally impactful for users, but still maintains that we only have to ever deal with one external issue tracker in all our features.
- Note that this constraint and condition happens when a user activates any given issue tracker. When this feature is released, and your GitLab instance already has multiple issue trackers enabled, this release doesn't change that fact. (We aren't doing any backfilling / changing of data.) If we get reports of errors / bugs, we will refer users to the documentation (and blog post) explaining what they should do, i.e., just toggle off/on their desired external issue tracker.
- The external trackers are:
