[FIX] stock: avoid to merge all moves

Some projects start to have real planning and in multiple
steps the `stock.move` that are not linked to a RFQ or a MO
are always merge together with the minimal date are result.

It's not flexible since you don't know the correct quantity
for a specific day. And once this quantity is received, you
don't know the next date.

We just add a system parameter for now and it will be modify
in master to be able to do this configuration for everyone.

X-original-commit: b9fffac7a8b6ccef2d957b5564ce615b2e1b0b36
Part-of: odoo/odoo#83430

addons/stock/models/stock_move.py

@@ -808,12 +808,15 @@ class StockMove(models.Model):
 
     @api.model
     def _prepare_merge_moves_distinct_fields(self):
-        return [
+        fields = [
             'product_id', 'price_unit', 'procure_method', 'location_id', 'location_dest_id',
             'product_uom', 'restrict_partner_id', 'scrapped', 'origin_returned_move_id',
             'package_level_id', 'propagate_cancel', 'description_picking', 'date_deadline',
             'product_packaging_id',
         ]
+        if self.env['ir.config_parameter'].sudo().get_param('stock.merge_only_same_date'):
+            fields.append('date')
+        return fields
 
     @api.model
     def _prepare_merge_negative_moves_excluded_distinct_fields(self):