Ask systemd for patiance, wait a bit longer when restarting the queued

I found that when updating MySQL systemd would restart the queued 3 times 100ms apart. While updating MySQL took a bit more then 0.3 seconds.

debian/aegir3-hostmaster.hosting-queued.service

@@ -6,6 +6,10 @@ After=mysql.service
 ExecStart=/usr/local/bin/drush --quiet @hostmaster hosting-queued
 User=aegir
 Restart=on-failure
+RestartSec=3
+StartLimitInterval=60
+StartLimitBurst=5
+
 
 [Install]
 WantedBy=multi-user.target