Stop sending mails for nagios alerts

It's just too much mail...

And there are other tools like nagstamon that are better suited to get
an overview what's failing.

Resolves: #8772

puppet/modules/site_nagios/files/configs/Debian/nagios.cfg

@@ -773,7 +773,7 @@ accept_passive_host_checks=1
 # service notifications when it is initially (re)started.
 # Values: 1 = enable notifications, 0 = disable notifications
 
-enable_notifications=1
+enable_notifications=0
 
 
 
@@ -1299,4 +1299,3 @@ host_perfdata_file_template=DATATYPE::HOSTPERFDATA\tTIMET::$TIMET$\tHOSTNAME::$H
 host_perfdata_file_mode=a
 host_perfdata_file_processing_interval=15
 host_perfdata_file_processing_command=process-host-perfdata-file-pnp4nagios-bulk-npcd
-