[FIX] point_of_sale: multiple installs inside a single request
[FIX] point_of_sale: multiple installs inside a single request

The modification of a helpdesk team may trigger the installation of some
modules.  The code was calling multiple times the installation of
modules (once per module to install), and this was triggering cache
misses on computed fields (probably because of a completely inconsistent
cache/registry).  We have grouped all the modules to install into a
single installation, and this fixes the issue.

Co-authored with Samuel Degueldre <sad@odoo.com>

closes odoo/odoo#37059

Signed-off-by: Raphael Collet (rco) <fcee45b878db1f337818c5c606c1542797080a40@openerp.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo