REST API: Correct the check for `$version` argument in `rest_handle_doing_it_wrong()`.

Move `WP_REST_Response` and `WP_Error` class names out of the translatable string.

Follow-up to [48327], [48361].

See #36271.
Built from https://develop.svn.wordpress.org/trunk@48367


git-svn-id: https://core.svn.wordpress.org/trunk@48136 1a063a9b-81f0-0310-95a4-ce76da25c4cd