This change removes OAuth2 for Gmail
as Delta Chat does not have a working
client ID anymore.
Tests are adjusted to test against Yandex
and MX queries for OAuth2 are always disabled
because they were only used to detect Google Workspace.
scripts/update-provider-database.sh checks out the provider database
and updates data.rs file,
making it easier to update.
CI uses this script to check that checked in data.rs
corresponds to the provider database repository.
