[FIX] mrp: properly handle subassembly production with same serial

If a subassembly was used as component in a finished good and both the
subassembly and finished good were unbuilt, the subassembly could not be
produced again with the same serial (specific use case: medical hardware
refurbishment, medical device is produced/packaged (subassembly), put as
a component into a procedure pack (finished good), both are returned and
unbuilt so the medical device can be refurbished and produced/packaged
again into a subassembly with the same serial).

The _is_finished_sn_already_produced function duplicates domain was
wrongly picking up stock move lines related to the unbuild of the
finished good, making the function wrongly returning True. This fixes
the search domain and adds a test to prevent regression.

closes odoo/odoo#132723

Signed-off-by: William Henrotin (whe) <whe@odoo.com>