web: kanban more menu is cropped on mobile

This commit removes some historical overflow-x properties needed
for old kanban views.

Steps to reproduce:
* Open Project App
* In kanban view and with one element, click on "more button" (3 dots)
* This menu will be truncated at the end. (BUG)

Task ID: 2058510

closes odoo/odoo#37727

Original-signed-off-by: Romeo Fragomeli <rfr@odoo.com>
X-original-commit: f4031c62
Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>