For the sale scope, we added a new 'pricelist_item_id' field, caching
the pricelist rule used for the price_unit and discount computation.
This feature uses the new `_get_pricelist_rule` method, which only returns
the pricelist rule matching the SOline values.
But the `_get_pricelist_rule` method still does all the price computation
for 'nothing'.
This commit skips the price computation (and the search of sub-rules if
the rule found is based on another pricelist).
closesodoo/odoo#103629
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>