app_containers: Rename the cleanup routine to cleanup()

exit is actually a keyword in bash

app_containers/.local/bin/run_app_container

@@ -5,7 +5,7 @@ die() {
   exit 1
 }
 
-exit() {
+cleanup() {
   rm -rf "$container_xdg_runtime"
   # Remove the temporary facl-based permissions
   setfacl -x u:$((user_on_host)) $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY
@@ -31,7 +31,7 @@ fi
 
 # Create a XDG_RUNTIME_DIR for guest on host
 container_xdg_runtime="$(mktemp -d -p /var/tmp)"
-trap exit EXIT
+trap cleanup EXIT
 
 # Link the current wayland session to the container's xdg runtime
 # Note that the session itself must be bind-mounted first