Describe the bug
Traefik remove tls header/footer from certificate when pass to authentik with X-Forwarded-TLS-Client-Cert header:
https://github.com/traefik/traefik/blob/master/pkg/middlewares/passtlsclientcert/pass_tls_client_cert.go#L326-L332

To Reproduce
Steps to reproduce the behavior:

1. Setup traefik reverse proxy
2. Pass a client certificate

Additional context
Code added in #14571