Bug 42777: Hide Website Privacy Preferences.

We hide the Website Privacy Preferences section, which controls the
"global privacy control" (GPC) and "do not track" (DNT) settings.

browser/components/preferences/privacy.inc.xhtml

@@ -358,7 +358,7 @@
     </vbox>
   </vbox>
 </groupbox>
-<groupbox id="nonTechnicalPrivacyGroup" data-category="panePrivacy" data-subcategory="nontechnicalprivacy" hidden="true">
+<groupbox id="nonTechnicalPrivacyGroup" data-category="panePrivacy" data-subcategory="nontechnicalprivacy" data-hidden-from-search="true" hidden="true">
   <label id="nonTechnicalPrivacyHeader"><html:h2 data-l10n-id="non-technical-privacy-header"/></label>
   <vbox id="nonTechnicalPrivacyBox">
     <hbox id="globalPrivacyControlBox" flex="1" align="center" hidden="true">