[FIX] sale_stock: improve module installation

Add _auto_init for stock_picking.sale_id
to speedup the module installation.

Since its related field, group_id.sale_id is also
created in sale_stock, creating the sale_id column is
enough.

opw-2638554

closes odoo/odoo#77437

X-original-commit: 6fb05387
Signed-off-by: Raphael Collet (rco) <rco@openerp.com>