We recently started trying to use O_TMPFILE without the kernel version
check, we gracefully degrade when it isn't available, and we don't give
operators any way to avoid the O_TMPFILE attempt -- logging at warning
seems way too noisy.
Change-Id: I8f42127fd6eb930282161930c65e8614f3e3175f
Related-Change: I3599e2ab257bcd99467aee83b747939afac639d8