Verify CI downstream project name before starting upstream pipeline

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

We were faced with one of those dreaded "bridge job forever stuck in pending status" issues recently.

I analyzed a number of related issues, namely #204378 (closed), #26746 (closed) & gitlab-runner#6583 (moved), but none applied. It turns out that in our case the

trigger:
    project: ...

configuration was simply pointing to a non-existent project. We had group/project but the project was recently moved to group/portal/project. It appears the redirection that is in place if you navigate to the old URL in the browser is not supported for the pipeline.

This request is for GitLab to verify that the configured project actually exists before starting the upstream pipeline.

Edited by 🤖 GitLab Bot 🤖