remove unnecessary code

src/client/js/services/AdminCustomizeContainer.js

@@ -74,16 +74,6 @@ export default class AdminCustomizeContainer extends Container {
     }
   }
 
-  /**
-   * Fetch highLight theme
-   */
-  async fetchHighLightTheme() {
-    const response = await this.appContainer.apiv3.get('/customize-setting/');
-    this.setState({
-      highlightJsCssSelectorOptions: response.data.highlightJsCssSelectorOptions,
-    });
-  }
-
   /**
    * Switch layoutType
    */