Removes the allow_client_tags metadata check from apply_client_tag_policy_pre_auth so
x-litellm-tags headers are always merged into request metadata, matching the post-auth
behavior in add_litellm_data_to_request. Updates pre-call tests accordingly and adds a
new test suite covering cascading credential renames into model rows.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>