fix(docs): add globalTimeout note to CI documentation

[Wu Shuwen (dajiaohuang)]

Summary

Fixes #42533

Add a note to the CI documentation explaining the relationship between GitHub Actions' timeout-minutes and Playwright's globalTimeout configuration option.

Problem

The recommended GitHub Actions workflow sets a job-level timeout-minutes but doesn't mention globalTimeout. When a test suite exceeds the job timeout:

• The run's conclusion is cancelled rather than failure
• The report upload step is skipped due to the !cancelled() guard
• Users get no report on precisely the runs where they need it most

Solution

Add a note explaining that setting globalTimeout below the job's timeout-minutes lets Playwright stop itself first, producing a proper failure with a full report instead of a cancelled run.

[Abdellah Ouadoudi (holistis)]

This matches the actual failure mode exactly, including the wording. Confirming from having hit this for real: a job with timeout-minutes: 20 and no globalTimeout killed a nightly run of ours 81 out of 164 times, the last 60-plus in a row, every single one ending cancelled with zero report written. Nothing in the run history told us anything was wrong until we went looking.

The note reads correctly to me. Thanks for picking this up and writing the fix.

[Dmitry Gozman (dgozman)]

Closing in favor of #42563.