Add a settings toggle to prevent running CI pipelines in draft MRs

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

Currently there are no options in either Settings > Merge Requests or Settings > CI/CD to prevent pipelines from being launched for MRs that are in draft status. There are already issues asking for an environment variable that would allow users to programmatically handle this case (e.g. #332419), but I think feature this might actually warrant a GUI toggle, in either of the Settings sections mentioned above.