Bug 1648024 - take ownership of correct mpris bus name for flatpak r=mtabara DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D90019

taskcluster/docker/firefox-flatpak/runme.sh

@@ -155,7 +155,7 @@ flatpak build-finish build                                      \
         --talk-name=org.freedesktop.ScreenSaver                 \
         --talk-name="org.gtk.vfs.*"                             \
         --talk-name=org.freedesktop.Notifications               \
-        --talk-name=org.mpris.MediaPlayer2.org.mozilla.firefox  \
+        --own-name="org.mpris.MediaPlayer2.firefox.*"           \
         --command=firefox
 
 flatpak build-export --disable-sandbox --no-update-summary --exclude='/share/runtime/langpack/*/*' repo build "$FLATPAK_BRANCH"