[FIX] website: make test works with more website than the data ones
[FIX] website: make test works with more website than the data ones

This test was raising an assert error if the DB has other websites than  the
data/demo ones.

As we have a new module in Odoo 13.0 (https://github.com/odoo/design-themes/pull/178)
which is creating 25 websites, and since the design-themes runbot is now
running tests, we were having a red design-themes runbot.

closes odoo/odoo#39008

X-original-commit: 5c7b446363fbec7b2a76a579794e0fac20d05271
Signed-off-by: Jérémy Kersten (jke) <56923a0c9ca793c07ff1df1013de5694062a27a6@openerp.com>

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