Checks tab should list duration of the "Preparing the "custom" executor" or "Executing "step_script" stage of the job script" step when the job times out

[JasonGross]

"Preparing the "custom" executor" took 26:32 here and 55:40 here. I'd like the corresponding checks tab (e.g., this) to say something like

Test has reached timeout on GitLab CI

This job has failed. If you need to, you can restart it directly in the GitHub interface using the "Re-run" button.

Steps taking more than 5 minutes:

• Preparing the "custom" executor (26:32)
• Executing "step_script" stage of the job script (1:32:28)

We show below the last 40 lines of the trace from GitLab (the complete trace is available here).

Or the description can be more concise, e.g., just saying "slowest step was ... taking ..." or something.

[SkySkimmer]

We're not using inria custom-runner anymore so maybe this doesn't matter anymore.