[5.x] Fix cannot use paginate/limit error when one is null

[jacksleight]

#10415 introduced a check to ensure that paginate and limit aren't used at the same time. However due to the has check a null limit value will pass as true even though it wouldn't be applied.

This becomes a problem when trying to pass variables through to tags where limit or paginate might be used:

{{ collection:articles :paginate="paginate" :limit="limit" }}

Statamic::tag('collection:articles', [
	'paginate' => $paginate,
	'limit' => $limit,
]);

I know you could filter the array or maybe use void in antlers, but it would be nice if you didn't have to worry about it. In this example there are conditions further up that ensure only one of those variables would be set.

The PR changes the check to use int so that a null value wont pass as true. The limit param check in the results method also uses int.