[FIX] web: Show scroll in report view search filter

Issue

	- Install "Accounting" module
	- Ensure there is more then 20 journals ( or
	  must do a zoom-in on the browser)
	- Go to Accounting -> Reporting -> Profit and Loss
	- Click on "Journals" filter

	Not all journals are displayed.

Cause

	No scroll or max-height set on dropdown.

Solution

	Set a max-height and an overflow:auto on `.dropdown-menu`
	and `o_dropdown_menu` css classes.

opw-2430101

closes odoo/odoo#64873

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>