Improve how "no search results" is handled

* Drop the ugly height: 100% hack and do it properly and remove TODO
* after( $suggestions.show() ) seems to not work as expected in recent
  jQuery versions. Changed it to manipulate the presence of 'hide'
  class properly.
* Consistency fix in a comment
* Fixed a bug where creating multiple ULS instances would break the
  "no search results" functionality. This is because we were appending
  a jQuery element wrapped in a $(). This is obviously a no-op and a
  regression when the template actually was a string and not jQuery.
  Fixed by using clone() on it.

https://phabricator.wikimedia.org/T175233

src/jquery.uls.core.js

@@ -221,7 +221,7 @@
 		},
 
 		/**
-		 * callback for results found context.
+		 * Callback for results found context.
 		 */
 		success: function () {
 			this.$resultsView.show();