CI timeout tuning for slow generation tests

Fixes on record

Merged to main. A stamp counts the issues a fix is linked to.

• #54143 test(ci): raise per-file timeout 140s → 300s to stop false timeouts

  merged to main

  files: infographic/ci-file-timeout-300/infographic.png, scripts/run_tests_parallel.py

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  • scripts/run_tests_parallel.py

    @@ -74,7 +74,16 @@
     
     # Per-file wall-clock cap. Override
     # via --file-timeout or HERMES_TEST_FILE_TIMEOUT.
    -_DEFAULT_FILE_TIMEOUT_SECONDS = 140.0 # set by observing the slowest file at commit time was ~100s in CI and adding some leeway
    +#
    +# Set to 300s (5 min) deliberately generous: the per-test subprocess
    +# isolation plugin spawns a fresh Python process per test, so a
    +# large-collection file pays N × (interpreter startup + import) of
    +# overhead before any test logic runs — and that overhead dilates under
    +# load on shared CI runners, producing false "no tests ran" timeouts on
    +# files that finish in ~100s on a quiet box. The Docker build matrix jobs
    +# take 7-10 min anyway, so this headroom costs nothing on total CI wall
    +# time while keeping a genuinely hung file bounded.
    +_DEFAULT_FILE_TIMEOUT_SECONDS = 300.0
     
     # Duration cache: maps relative file paths to last-observed subprocess
     # wall-clock seconds. Used by ``--slice`` to distribute files across