Table: Fix incorrect condtition for rendering table filter (#29165) (#29181)

(cherry picked from commit f28ba27ca2)

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

packages/grafana-ui/src/components/Table/DefaultCell.tsx

@@ -49,7 +49,7 @@ export const DefaultCell: FC<TableCellProps> = props => {
           {value}
         </a>
       )}
-      {showFilters && cell.value && <FilterActions {...props} />}
+      {showFilters && cell.value !== undefined && <FilterActions {...props} />}
     </div>
   );
 };