Proxy Protocol Fixed A Bug Where Passthrough Tlvs

Fix: CVE-2026-47692 <https://github.com/envoyproxy/envoy/security/advisories/GHSA-wh36-hm39-mm3r>_

Fixed a bug where passthrough TLVs combined with added TLVs could exceed the maximum length, resulting in a mismatch between the size reported in the header and the number of bytes written. This could allow a smuggled request from the host writing the PROXY protocol header to the upstream host. This behavioral change can be reverted by setting the runtime guard envoy.reloadable_features.proxy_protocol_remove_too_long_tlvs to false.