UI tip for why job Retry is not allowed for non-draft MR with merge trains enabled

Release notes

TBD

Problem to solve

For projects with Merge Trains enabled, once an MR is no longer a Draft, you can't re-run individual jobs; the only option is to re-run the entire pipeline with the "Run Pipeline" button at the top of the Pipelines tab. The problem is there is no visual cue explaining why user cannot re-run individual jobs in a non-draft MR.

Further details

Given this is how MRs for projects with merge trains is intended to work, it is necessary to keep the MR in Draft mode if there is a need to re-run individual jobs.

Proposal

Provide a visual cue the UI, possibly near where a Retry button would normally appear, that explains why Retry is not possible for this use case.