[FIX] web: kanban: drag column with sample data

Before this commit, in a grouped kanban view with sample data (e.g.
crm.lead), one could toggle the 'settings' dropdown menu of a
group, and then drag&drop the group by clicking on the muted "Fold"
item in the dropdown.

After this commit, dragging a column is only possible by clicking
on the column title (but not on the 'config' or '+' icons, nor the
config dropdown).

Task 2290197

closes odoo/odoo#54179

X-original-commit: 58c38a024c96eba3469c142a8422b7bd0ab54ea4
Signed-off-by: Mathieu Duckerts-Antoine <Polymorphe57@users.noreply.github.com>
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>