Remove some dead code in files app

Signed-off-by: Varun Patil <varunpatil@ucla.edu>

apps/files/js/app.js

@@ -139,9 +139,6 @@
 
 			this._setupEvents();
 
-			this._debouncedPersistShowHiddenFilesState = _.debounce(this._persistShowHiddenFilesState, 1200);
-			this._debouncedPersistCropImagePreviewsState = _.debounce(this._persistCropImagePreviewsState, 1200);
-
 			if (sessionStorage.getItem('WhatsNewServerCheck') < (Date.now() - 3600*1000)) {
 				OCP.WhatsNew.query(); // for Nextcloud server
 				sessionStorage.setItem('WhatsNewServerCheck', Date.now());