Remove duplication of "No matches found" message on multi select2 clearing

*Steps to reproduce:*
1. Select all items in a multi select input and make sure that _"No matches found"_ message is shown.
2. Trigger clearing on the input with _val_, for example: 
```javascript
$('some-component-selector').select2('val', '');
```
*Expected Result:* the input is cleared and _"No matches found"_ message is hidden.

*Actual Result:* _"No matches found"_ message is shown as many times as we clear the input.