[FIX] mrp: handle keyError when workorder(s) deleted

If applied, this commit will solve the issue of keyError when we confirm the
manufacturing order and work order (s) are deleted.

Steps to produce:
- Configure BOM with 'Operations'.
- Set operations in the 'Consumed in Operation' field which is in 'Components'.
- Create MO using that BOM.
- Delete the work order(s) from MO.
- Click on the 'Confirm' button.

Fix this issue when the work order is not available for that operation,
setting False in stock.move record(s).

sentry - 4171798106

closes odoo/odoo#122115

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