[IMP] stock: unreserve only quantity required if available quantity is less...

[IMP] stock: unreserve only quantity required if available quantity is less than quantity required when action_done on stock move.

Example:
Now there is this behaviour
Inventory quantity 4
Reserved quantity 3
Available quantity 1
If i do a stock move of 2 pieces, it will unreserve ALL the stock move of the product.

With this PR it will unreserve only the pieces that are required minus the available quantity not reserved , in this case 2 (new stock move) - 1 (available quantity) = 1

closes odoo/odoo#119999

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