Bug 1661301 - Remove obsolete comment. r=botond

This comment has been obsolete since https://hg.mozilla.org/mozilla-central/rev/e122d0043843
when APZ started handling wheel events even with the pref enabled.

Depends on D88307

Differential Revision: https://phabricator.services.mozilla.com/D88308

modules/libpref/init/StaticPrefList.yaml

@@ -7665,7 +7665,6 @@
   value: false
   mirror: always
 
-# This affects whether events will be routed through APZ or not.
 - name: mousewheel.system_scroll_override_on_root_content.enabled
   type: RelaxedAtomicBool
 #ifdef XP_WIN