ref(cells): Unregister cells.use-control-org-listing (#117556)

This cleans up the temporary option used to transition the org list API.
The rollout is now complete.

Author: lynnagara

src/sentry/options/defaults.py

@@ -3724,14 +3724,6 @@
     default=0.0,
     flags=FLAG_AUTOMATOR_MODIFIABLE,
 )
-# TODO(cells): Fully rolled out and no longer read anywhere. Unregister once the
-# value is removed from sentry-options-automator.
-register(
-    "cells.use-control-org-listing",
-    type=Bool,
-    default=False,
-    flags=FLAG_AUTOMATOR_MODIFIABLE,
-)
 
 # SCM