WebUI tests: fix failing of tests due to unclicable label
    
    Checkbox label is no longer clickable, most tests fail with error like this:
    
    AssertionError: Can't click on checkbox label: table.table
    Message: Element is not clickable at point (37, 340.3999938964844). Other element would receive the click:
    <input class="standalone" id="cn18" value="itest-group" name="cn" type="checkbox">
    
    The checkbox is clickable directly without the label, this patch provides according fix.
    
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>