[FIX] sale: Unpredictable sales team

Steps to reproduce the bug:
- Install website_crm_score
- Add Mitchell Admin in 2 sales teams
- Create a quote
- Play with the ordering of sales teams sequences

Bug:

The default sales team will be different at quote creation, partner
selection, etc. and will basically be unpredictable (while you would
expect it to take the first team the salesperson is a member of in
the order of the sequence)

The problem is an inconsistent use of the _get_default_team_id method
and the sales team of a user. Since the website score module add the
possibility to have a user member of more than one team, using the
team of the user is bad. You should use the method all the time
for consistent results.

opw:2196934

closes odoo/odoo#45618

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>