Remove media-session from this tree

It is now available as a separate project in
https://gitlab.freedesktop.org/pipewire/media-session

The code required by pw-reservice has moved to src/tools/reserve.{c|h}

.gitlab-ci.yml

@@ -317,13 +317,6 @@ doccheck:
     - .build_on_fedora
   stage: analysis
   script:
-    # Check that each media session module has a \subpage entry
-    - git grep -h -o -e "\\\page page_media_session_module_\w\+" | cut -f2 -d' ' > media_session_pages
-    - cat media_session_pages
-    - |
-      for page in $(cat media_session_pages); do
-          git grep -q -e "\\\subpage $page" || (echo "\\page $page is missing \\subpage entry in doc/media-session.dox" && false)
-      done
     # Check that each pipewire module has a \subpage entry
     - git grep -h -o -e "\\\page page_module_\w\+" | cut -f2 -d' ' > pipewire_module_pages
     - cat pipewire_module_pages