Consider re-enabling shared runners in the project settings.
Summary
The shared runners were turned off in this project. I guess they aren't needed as the project/group runners can handle the workload? Unfortunately, what this means is that when contributors fork the project to make contributions, they inherit the disabled shared runners setting, and their pipelines get stuck. For example: !2256 (comment 727306830)
We should consider turning that setting back on so that when contributors fork the repo, they'll be able to immediately start submitting MRs with running pipelines without any extra configuration.