[IMP] web,*: do not deploy services in tests

*mail,point_of_sale,web_editor,website

In the tests, required services are deployed for each test
independently. There is no need to have, in additon, all services
deployed globally. Worse, it could conflict and lead to unexpected
results.

This commit ensures services are no longer deployed globally in
tests. It turns the module 'web.env' into a declarative module with
no side-effect, by moving the service deployment to main.js, which
isn't added to the tests page.

Task 2287397

closes odoo/odoo#53817

Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>