Remove a number of extensions used by systemd INI files which are too common (see github-linguist#7161)

Author: vorburger

lib/linguist/languages.yml

@@ -8484,22 +8484,12 @@ desktop:
   # systemd unit-file types; extensions from
   # https://www.freedesktop.org/software/systemd/man/latest/systemd.syntax.html
   - ".automount"
-  - ".device"
-  - ".link"
   - ".mount"
   - ".netdev"
-  - ".network"
   - ".nspawn"
-  - ".path"
-  - ".scope"
   - ".service"
-  - ".slice"
-  - ".snapshot"
   - ".socket"
-  - ".swap"
-  - ".target"
   - ".timer"
-  - ".unit"
   tm_scope: source.desktop
   ace_mode: text
   language_id: 412