[FIX] sale: recompute delivered qty

- Create a product A of type "Service", Invoice based on "Milestones",
Service Tracking "Create a task in a new project".
- Create a new SO with A, confirm.
- Go the to task associated to the SO, go to "Timesheets" tab, add an
entry
- In the SO, edit the delivered quantity
- Create invoice, validate

Back to the SO, delivered quantity is reset to 0.

We make sure to filter out SO lines which have a delivered quantity set
manually.

Introduced by d6ad2222.

opw-1982020

closes odoo/odoo#33991

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>