CI evidence overturns the chunking half of this branch. Splitting the
singleton bucket into 8 chunks made the job run 11m27s and go red, where
the unchunked bucket passes in ~1m31s on a concurrent PR. The duration
matches the 600s chunk watchdog, i.e. a chunk wedged rather than merely
running slowly -- the "these suites co-locate in one process" comment was
describing a real coupling, so restore it and the original plan entry.
The failure-attribution change is kept and is independently justified:
this run is precisely the case where a bare "exit code 137" cannot
distinguish the watchdog from the OOM killer.
Muhammad Mustaqeem
21a4d0b2fa