Fix for filter for 0 in ajaxlists (cherry picked from commit c9f5fbf)
Update ajaxlistcomponent.php

Fix for reported Bug
https://bugs.oxid-esales.com/view.php?id=5752
(cherry picked from commit 85b2b82)
Removed not used variable (cherry picked from commit 9ed5de8)
0005752: You can't search for 0 in Backend Ajax Masks; Added test case with filter 0 (cherry picked from commit c35939f)