fix(aibridge): strip proxy headers from bridge requests to fix Bedrock SigV4 signing by ssncferreira · Pull Request #26019 · coder/coder

…k SigV4 signing

On bridge routes aibridge acts as a client, not a proxy. Proxy headers
(X-Forwarded-For, etc.) from the inbound request were forwarded on
the outbound request and included in the SigV4 signed-headers set. Any
in-transit modification by an egress proxy invalidated the signature,
causing AWS to reject the request with a 403.

Strip proxy headers in PrepareClientHeaders so they are not present
when the SigV4 signer runs.