[FIX] web: web_client o_content is scrollable, not action manager

Go on a kanban view with a scroll bar
scroll all the way down
Open a record in form view

Use the breadcrumb to go back to the kanban

Before this commit, the kanban was re-opened
but the position were we were before opening the record was lost

This was due to 40dd1219
which refactors the dom, puting the action manager on top of controllers

After this commit, when re-opening the kanban, we end up at the same position
we left it at

OPW 2074077

closes odoo/odoo#39111

X-original-commit: c0d48878c452b256859f067186567c126d8de27e
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>