[IMP] stock: Remove domain on source/destination on Operation Details

When doing an internal trasnfer, you can choose any destination
location in the header, but not on the line

This is problematic when doing a pick-pack-ship transfer. For the pick
move, you may want to change the source destination location (maybe another
warehouse why not) but as the transfer is already validated you cannot
modify it on the form. But with the Operation Details (Pencil button) you
can modify the source/destination location. The only problem is that a domain
is forcing the user to choose a source destination that is a child of the source
destination on the transfer, which makes impossible to choose a destination on
another warehouse. This tool is pretty much advanced, so we don't need to be so
restrictive.

addons/stock/views/stock_pack_operation_views.xml

@@ -21,8 +21,8 @@
                         </div>
                     </group>
                     <group string="Locations" groups="stock.group_stock_multi_locations">
-                        <field name="location_id" domain="[('id', 'child_of', picking_source_location_id)]"/>
-                        <field name="location_dest_id" domain="[('id', 'child_of', picking_destination_location_id)]"/>
+                        <field name="location_id"/>
+                        <field name="location_dest_id"/>
                     </group>
                     <group string="Packages" groups="stock.group_tracking_lot">
                         <field name="package_id" attrs="{'required': [('product_id', '=', False)]}" context="{'location_id': location_id}"/>