fix: remove error message about sessions that can't be deleted

Not a nice solution, but message are kept when using ``DEBUG``.

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

bin/compose

@@ -353,7 +353,10 @@ clean_unused_sessions() {
     for f in "$SESSION_DIR/"*; do
         [ -e "$f" ] || continue
         is_volume_used "$f" && continue
-        rm -f "$f"
+        ## XXXvlab: the second rmdir should not be useful
+        rm -f "$f" >/dev/null || rmdir "$f" >/dev/null || {
+            debug "Unexpected session remnants $f"
+        }
     done
 }