[lazerg]

Summary:

stopMetroServer in Fantom's global teardown races the Metro server's close against a 5 second setTimeout, but never clears that timer when close wins. The pending timer keeps Node's event loop alive, so every yarn fantom run hangs for about 5 seconds after the summary and Jest prints "Jest did not exit one second after the test run has completed". This clears the timer once the race settles.

Fixes #59699

Changelog:

[INTERNAL] [FIXED] - Clear Fantom's Metro shutdown timer once the server closes

Test Plan:

Ran the same close-vs-timeout race against a plain Node http server: without clearTimeout the process exits about 5 s after teardown returns, with it the process exits right away. yarn flow check, eslint and prettier pass on the file. I don't have Fantom's tester built locally, so I didn't run yarn fantom itself.