[FIX] stock: free reservation over reserve

Usecase to reproduce:
- 6 units in stock
- reserve 3 units on a move
- reserve 3 units on another move
- validate a third move with 1 unit

It raise the error could not reserve more than you have in stock.
It happens because when free reservation stole reservation from
an exisiting move with too much quantity available, it continues the
loop instead of stopping.

This commit stop the loop once we have enough quantity taken.

opw-1895578

closes odoo/odoo#27935