systemd: disable avahi-daemon and dnf-makecache

Especially dnf-makecache is senseless as its state will not survive VM
restart, but it takes a lot of CPU time.

vm-systemd/75-qubes-vm.preset

@@ -21,8 +21,10 @@ disable alsa-restore.service
 disable auditd.service
 disable avahi.service
 disable avahi-daemon.service
+disable avahi-daemon.socket
 disable backuppc.service
 disable cpuspeed.service
+disable dnf-makecache.timer
 disable fedora-autorelabel.service
 disable fedora-autorelabel-mark.service
 disable ipmi.service