[IMP] base_address_partner: optimise transfer betwen parent and child

Mostly a concern during bulk import of partners with parents.

First remove syncing extended fields, that seems completely
unnecessary since the street gets sync'd and will get split through the
normal process (updating the sub-fields), by also syncing the split
fields we're redundantly calling _set_steet and rewriting the address
we just sync'd.

Second if write()ing both the country and street, the override would
then go and re-write the street based on what had *just* been split
into sub-street fields, which could waste a lot of time during the
import post-process as address fields get moved back and forth between
parents and children leading to *lots* of writing both country and
address together, we're talking:

 ncalls  tottime  percall  cumtime  percall filename:lineno(function)
10002/2    0.111    0.000  344.390  172.195 res_partner.py:181(write)
[...]
      2    0.455    0.228  165.264   82.632 base_address_extended.py:41(_set_street)

My initial instinct was to just add the country_id to _set_street and
remove the write override but it would break
88ff6beb01: if the country alone is
updated on a partner, we do want to re-format the "unified" address
based on individual fields and the new country's format.

Note: it might be that the logic would be more sensible by inversing
the entire thing, such that the split fields are the proper
source (regular stored fields) and street is converted to a computed
field instead, but that'd be a larger model change. Seems like it'd
make more sense though, at least given what the modules attempts to
do (OTOH the module probably fails
https://www.mjt.me.uk/posts/falsehoods-programmers-believe-about-addresses/
in just about all the ways).

addons/base_address_extended/models/base_address_extended.py

@@ -33,11 +33,6 @@ class Partner(models.Model):
     street_number2 = fields.Char('Door', compute='_split_street', help="Door Number",
                                  inverse='_set_street', store=True)
 
-    @api.model
-    def _address_fields(self):
-        """Returns the list of address fields that are synced from the parent."""
-        return super(Partner, self)._address_fields() + ['street_name', 'street_number', 'street_number2']
-
     def get_street_fields(self):
         """Returns the fields that can be used in a street format.
         Overwrite this function if you want to add your own fields."""
@@ -144,7 +139,7 @@ class Partner(models.Model):
 
     def write(self, vals):
         res = super(Partner, self).write(vals)
-        if 'country_id' in vals:
+        if 'country_id' in vals and 'street' not in vals:
             self._set_street()
         return res