ui: Utils: delete_if_default: add values by correct type

ui: Utils: delete_if_default: add values by correct type

if 'delete' is an Array, we want to push into it, not append a string
this could be an issue when we use an edit window with multiple inputpanels
and deleteEmpty set on some fields

we then could have an aray like this:

values: {
    delete: [
	'foo',
	'bar',
	'baz, qux',
    ],
},

which the edit window does not handle correctly anymore
(it only does string splitting if 'delete' itself is a string)

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