feat: remove SAML provider admin views from openedx-platform

Other steps taken too:

- Add ADR and URL routes comment for migrated SAML admin views to
  help ensure people don't inadvertantly register conflicting URL routes.
- Remove validate_uuid4_string, convert_saml_slug_provider_id, and
  fetch_metadata_xml from third_party_auth/utils.py (migrated to
  edx-enterprise)
- Remove test_convert_saml_slug_provider_id test and import
- Add TestCreateOrUpdateBulkSAMLProviderData test class with 4 tests
  covering create, update, bulk_update, and multiple keys paths
- Remove unused imports: logging, requests, uuid.UUID

ENT-11567

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: pwnage101