Database: Add `ANSI` to the list of incompatible SQL modes.

Starting with MySQL 5.7.5, the `ANSI` mode implies `ONLY_FULL_GROUP_BY`, which is already listed in `wpdb` as incompatible per [27072].

When `ANSI` is enabled on MySQL 5.7.5+, `ONLY_FULL_GROUP_BY` remains enabled even after being "unset" by `wpdb::set_sql_mode()`.

To prevent this, the `ANSI` mode should also be listed as incompatible. It is not enabled on default MySQL installations.

Props jnylen0.
Fixes #48377.
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