Remove deprecated and unused `searchTypeaheadEnabled` method (#39797)

frontend/src/metabase/lib/settings.ts

@@ -206,13 +206,6 @@ class MetabaseSettings {
     return this.get("enable-password-login");
   }
 
-  /**
-   * @deprecated use getSetting(state, "search-typeahead-enabled")
-   */
-  searchTypeaheadEnabled() {
-    return this.get("search-typeahead-enabled");
-  }
-
   /**
    * @deprecated use getSetting(state, "anon-tracking-enabled")
    */