[FIX] point_of_sale,pos_restaurant: fix auto FloorScreen when idle

- Restaurant shops should automatically go back to floor screen when
idle. However, after https://github.com/odoo/odoo/pull/89712

, this
feature is broken when pos_hr is also installed - the screen doesn't
automatically go back to floor screen.
A simple fix is to clear the tempScreen name when the shown tempScreen
is closed. Note that this change is fine because when tempScreen is closed
(!isShown), the `tempScreen.name` information has no use.

- Once the `idleTimer` is set, it is never removed. This means that
even if the conditions to go back to the FloorScreen at the current
time T are not satisfied, the `_actionAfterIdle` is still run.
Checking if the action can be done once triggered fix the issue.

closes odoo/odoo#92058

Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>