Remove the now unused FSGlobalButtonFlashOverride setting

indra/newview/app_settings/settings.xml

@@ -18871,17 +18871,6 @@ Change of this parameter will affect the layout of buttons in notification toast
       <key>Value</key>
       <real>1.25</real>
     </map>
-  <key>FSGlobalButtonFlashOverride</key>
-  <map>
-    <key>Comment</key>
-    <string>If enabled, button flash rate and count will be overridden globally.</string>
-    <key>Persist</key>
-    <integer>1</integer>
-    <key>Type</key>
-    <string>Boolean</string>
-    <key>Value</key>
-    <integer>0</integer>
-  </map>
   <key>FSTagShowDistanceColors</key>
   <map>
     <key>Comment</key>

indra/newview/skins/default/xui/en/panel_preferences_UI.xml

@@ -417,17 +417,6 @@
          top_pad="4"
          width="256" />
 
-        <check_box
-         control_name="FSGlobalButtonFlashOverride"
-         type="string"
-         left="5"
-         top_pad="6"
-         follows="left|top"
-         height="12"
-         layout="topleft"
-         name="ButtonFlashing"
-         width="128"
-         label="Flashing IM tabs override"/>
         <slider
          control_name="FSButtonFlashCount"
          decimal_digits="0"
@@ -441,7 +430,7 @@
          min_val="0"
          max_val="16"
          name="ButtonsFlashCount"
-         top_pad="2"
+         top_pad="6"
          width="471" />
         <slider
          control_name="FSButtonFlashRate"