ui: datastore/Summary: change destroy listener

by using beforedestroy instead of destroy (like we do everywhere else)
to avoid race condition when the controller has
already removed some handlers on destruction

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

www/tape/ChangerStatus.js

@@ -668,7 +668,7 @@ Ext.define('PBS.TapeManagement.ChangerStatus', {
 
     listeners: {
 	deactivate: 'cancelReload',
-	destroy: 'cancelReload',
+	beforedestroy: 'cancelReload',
     },
 
     tbar: [