Switch to dh_installsystemd

debian/rules

@@ -121,8 +121,7 @@ binary-arch:	build
 		do dh_link usr/lib/$(package)/bin/$$bin usr/sbin/$$bin; done
 	mv debian/mailman/usr/sbin/arch debian/mailman/usr/sbin/mmarch
 	dh_installman
-	dh_systemd_enable
-	dh_systemd_start
+	dh_installsystemd
 	dh_installdebconf
 	dh_installexamples templates/* debian/mm_cfg.py \
 		debian/mailman/usr/lib/$(package)/Mailman/Defaults.py