Bug 1847282 - Change the default for pull-to-refresh to disabled

Changing the default for the feature while we work on fixing some of the
known glaring bugs that users are facing.

app/src/main/java/org/mozilla/fenix/utils/Settings.kt

@@ -1425,7 +1425,7 @@ class Settings(private val appContext: Context) : PreferencesHolder {
 
     var isPullToRefreshEnabledInBrowser by booleanPreference(
         appContext.getPreferenceKey(R.string.pref_key_website_pull_to_refresh),
-        default = true,
+        default = Config.channel.isNightlyOrDebug,
     )
 
     var isDynamicToolbarEnabled by booleanPreference(