[FIX] crm: fix res.partner creation from Leads

- Go to CRM > Settings and activate Leads
- Go to CRM > Leads and create 2 Leads with a different phone number
- Select the 2 created Leads and in Action menu, select Send email
- Make sure that "Lead/Opportunity: Mass Mail" is selected as template
- Send it
- Go to Contacts
2 Contacts have been created from the Leads, but both have the same phone number.

The issue comes from the override `default_get` of `res.partner` in crm module.
It is using `active_id` from context to fetch the Lead to populate Partner data.
This cannot work when several Leads are selected as the same `active_id` is used
for all of them.

opw-2333819

closes odoo/odoo#57638

X-original-commit: a84dcfb9475051082c6103f81bfa231ea50ed157
Signed-off-by: Anh Thao PHAM <kitan191@users.noreply.github.com>

addons/crm/models/res_partner.py

@@ -18,7 +18,7 @@ class Partner(models.Model):
     def default_get(self, fields):
         rec = super(Partner, self).default_get(fields)
         active_model = self.env.context.get('active_model')
-        if active_model == 'crm.lead':
+        if active_model == 'crm.lead' and len(self.env.context.get('active_ids', [])) <= 1:
             lead = self.env[active_model].browse(self.env.context.get('active_id')).exists()
             if lead:
                 rec.update(