lightdm.service: Remove obsolete references

Remove startup-tags condition, because we only have lightdm now. Remove
dependencies on startup-tags.service as well, which would not be needed
even if we used the tags.

Also, remove After= dependency to nvidia.service, because this is now
handled by nvidia.service with a Before=display-manager.service
dependency.

misc_systemd_units/lightdm.service

@@ -1,8 +1,5 @@
 [Unit]
-Description=LightDM
-Wants=nvidia.service startup-tags.service
-After=systemd-user-sessions.service nvidia.service startup-tags.service
-ConditionPathExists=/node/tags/lightdm
+After=systemd-user-sessions.service
 
 [Service]
 ExecStart=/usr/bin/lightdm