[FIX] base: tests, reflect unaccent behavior of 5e3de76f

Since the revision
5e3de76f

The `::text` is included within the `unaccent` call
The expession tests have never been changed according
to this change of behavior in the building of the unaccented
queries. This has never been detected by runbot because
you need to start the Odoo server with the option
`--unaccent`
and to create the database with the unaccent extension
`CREATE EXTENSION unaccent`
to be able to fail the former tests,
and this is not the case on runbot.