Bug 1772399: Disable dom.select_events.textcontrols.selectstart. r=edgar

Disabled pref dom.select_events.textcontrols.selectstart also for nightly build.

Differential Revision: https://phabricator.services.mozilla.com/D153561

modules/libpref/init/StaticPrefList.yaml

@@ -3589,7 +3589,7 @@
 
 - name: dom.select_events.textcontrols.selectstart.enabled
   type: bool
-  value: @IS_NIGHTLY_BUILD@
+  value: false
   mirror: always
 
 - name: dom.separate_event_queue_for_post_message.enabled