The child-log-flood regression built one 30M-char argument string, which under
the 64 MB addressSpaceMb died on RLIMIT_AS during construction (exit 120) before
the flush trigger under test could run, so it failed on Linux CI. Write the
flood in 1 MiB chunks under a 512 MiB address space instead: the argument str is
never itself the allocation under test, the fixed serialized-cost trigger keeps
the pending tail bounded to a few MiB, and the run completes at the marker; the
pre-fix char-count trigger accumulates the whole ~200 MiB and its ~1.2 GiB
settlement encode breaches RLIMIT_AS. Mirrors the addressSpaceMb budget the
existing oversized-completion tests use.
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