planet/hm/thunar: upstream systemd user service should not run

[dixslyf]

Currently, the user service for Thunar from upstream runs on start-up (probably for running as a daemon). This would have been fine, but it seems to mess with the PATH that Thunar sees. For example, using the Open Terminal Here custom action results in a ton of errors from fish due to programs not being in PATH. Thunar also does not seem to have read the mimeapps.list. Stopping the service and running Thunar manually is a workaround for now.