LibWebView+UI: Remove native do-not-track setting

Author: https://github.com/trflynn89
Commit: 920170f60a
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4194
Reviewed-by: https://github.com/AtkinsSJ

UI/Qt/Tab.h

@@ -90,8 +90,6 @@ public:
 
     void set_preferred_languages(ReadonlySpan<String> preferred_languages);
 
-    void set_enable_do_not_track(bool);
-
     bool url_is_hidden() const { return m_location_edit->url_is_hidden(); }
     void set_url_is_hidden(bool url_is_hidden) { m_location_edit->set_url_is_hidden(url_is_hidden); }