journald: slightly bump OOM adjust for journald (#13366)

If logging disappears issues are hard to debug, hence let's give
journald a slight edge over other services when the OOM killer hits.

Here are the special adjustments we now make:

 systemd-coredump@.service.in OOMScoreAdjust=500
 systemd-journald.service.in  OOMScoreAdjust=-250
 systemd-udevd.service.in     OOMScoreAdjust=-1000

(i.e. the coredump processing is made more likely to be killed on OOM,
and udevd and journald are less likely to be killed)

src/shutdown/shutdown.c

@@ -508,7 +508,6 @@ int main(int argc, char *argv[]) {
                         log_error_errno(errno, "Failed to execute shutdown binary: %m");
                 } else
                         log_error_errno(r, "Failed to switch root to \"/run/initramfs\": %m");
-
         }
 
         if (need_umount || need_swapoff || need_loop_detach || need_dm_detach)