[FIX] res_partner: default image in testing
[FIX] res_partner: default image in testing

When in testing mode there is no need to compute the default image. Indeed
this information is rarely necessary for testing purpose. For the whole set
of Odoo tests, removing the default image computation in test mode makes
a gain of ~10 minuts of computation.

ygol/odoo,dfang/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo,ygol/odoo,ygol/odoo,hip-odoo/odoo,dfang/odoo,hip-odoo/odoo,hip-odoo/odoo,dfang/odoo,dfang/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,ygol/odoo,ygol/odoo,hip-odoo/odoo