When shutting down an allocation that ends up needing to be
force-killed, we're getting a spurious "OOM Killed (137)" message on
the task termination event. We introduced this as part of cgroups v2
support because the Docker daemon isn't detecting the container status
correctly. Although exit code 137 is the exit code we get for
OOM-killed processes, that's because OOM kill is a `SIGKILL`. So any
sigkilled process will get that exit code.