[FIX] web: not able to scroll in long grouped kanban

Due to commit odoo/odoo@f4031c62f97fa170b74b0d13a0856b7d58ed4da6
it was not more possible to scroll in a grouped kanban.

Steps to reproduce:
* Go to project app
* Select a project with a few numbers of task
* Create as need new task to have more task than visible on the screen
* Try to scroll (BUG)

Note: we also fix the swipe in empty column

opw-2080491

closes odoo/odoo#39168

X-original-commit: 023941e25cae34e60eaabcc54841b3d908a59414
Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>

addons/web/static/src/scss/kanban_view_mobile.scss

@@ -2,7 +2,7 @@
     .o_kanban_view.o_kanban_grouped {
         display: block;
         position: relative;
-        overflow: hidden;
+        overflow-x: hidden;
 
         .o_kanban_mobile_tabs {
             display:flex;