In my opinion, the .env.local should not overwrite .env.test
variables. When using .env.local for tests, the tests are not
transparent and can't be executed for example on a CI server.

As the documentation says, the `.env.local` is here for **local**
overwrites. They should not overwrite a test specific variable. Tests
should be run on every machine in every environment and shouldn't
require any specification of environment variables. (My opinion)