abstraction/exo-open: Remove dbus deny rule

Abstractions should not generally include deny rules as this can unduly
constrain profiles which include them due to the precedent matching rules
between deny vs allow rules. Also as per the comment, this is not required
for exo-open to work, so simply omit it from the abstraction for
now. Finally, in Ubuntu, the evince profile includes the exo-open
abstraction and this deny rule causes evince to fail to initialise
correctly as it then assumes it cannot use gvfs.

Signed-off-by: Alex Murray <alex.murray@canonical.com>

profiles/apparmor.d/abstractions/exo-open

@@ -51,13 +51,6 @@
 
   /{,usr/}bin/which rix,
 
-  # Deny DBus
-
-  # for GTK error message dialog, not required exo-open to work.
-  deny dbus send
-    bus=session
-    path=/org/gtk/vfs/mounttracker,
-
   # System files
 
   /etc/xdg/{,xdg-*/}xfce4/helpers.rc r,