Use history.replaceState instead of history.pushState

This removes the URL with the URL parameter setlang from the history.
A click on history back doesn't show the URL parameter setlang anymore.

Change-Id: I0ea8c4508bedd9758a1cebbe8ecb2a7113bf8538

resources/js/ext.uls.setlang.js

@@ -94,7 +94,7 @@
 
 		$cancelBtn.on( 'click', function () {
 			var urlWithoutSetlang = removeParam( 'setlang' );
-			history.pushState( null, 'no-setlang-url', urlWithoutSetlang );
+			history.replaceState( null, 'no-setlang-url', urlWithoutSetlang );
 			ulsDialog.close();
 		} );
 	}