[nagios-nrpe-server] Add an override for unit file
I propose to add
nagios-nrpe-server need to be always running.
The unit file uses
OOMScoreAdjust=-500 to not to kill the service by OOMkill but it is sometimes useless as NRPE cannot fork:
Failed at step EXEC spawning /bin/rm: Cannot allocate memory
Restart=always will keep relaunching the process if it fails due to memory allocation. By the time OOMkiller kills another process to free the RAM.