[FIX] sale: Wrong currency conversion with pricelist

Steps to reproduce the issue:

- Let's consider a company C in $ and the rate conversion from $ to € is 0.5
- Let's consider a product P
- Let's consider a pricelist PL1 in € such as P is set to 100€
- Let's consider a pricelist PL2 in $ such as P id set to 100$
- Create a sale order SO with PL1
- Create a line with P

Bug:

The unit price of P was 200€ instead of 100€ because field currency_id was not set on the line
when trying to pass it to function _get_tax_included_unit_price

opw:2789324

closes odoo/odoo#86483

Signed-off-by: Simon Goffin <sig@odoo.com>