fix #5074: notify: sendmail: smtp: fix mailto/mailto-user parameter deletion

by doing a cbind of isCreate to the top-level widget so that cbind in
the nested widgets for deleteEmpty works.

In the GUI, when a sendmail/smtp target is edited and either
'Additional Recipients' or 'Recipients' is completely removed (only
possible if the other field contains a value), parameter deletion did
not work properly. After applying the changes, the old value would
still be in place.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Lukas Wagner <l.wagner@proxmox.com>
Reviewed-by: Lukas Wagner <l.wagner@proxmox.com>

src/panel/EmailRecipientPanel.js

@@ -19,6 +19,9 @@ Ext.define('Proxmox.panel.EmailRecipientPanel', {
 	{
 	    layout: 'anchor',
 	    border: false,
+	    cbind: {
+		isCreate: '{isCreate}',
+	    },
 	    items: [
 		{
 		    xtype: 'pmxUserSelector',