Remove Content-Length from HTTP Connect Custom response

[saurabhbhatia-stripe]

Summary

Currently while using HTTP Connect custom handlers it responds with content-length as 0 along with HTTP/1.0 200 OK. This is not RFC-9110 compliant which states that a server MUST NOT send any Transfer-Encoding or Content-Length header fields in a 2xx (Successful) response to CONNECT.

Old HTTP Connect Custom Response

HTTP/1.0 200 OK
Content-Length: 0

New HTTP Connect Custom Response

HTTP/1.0 200 OK

Changes

We are setting ContentLength as -1 which marks it as unknown and removes content length while writing response

Snippet from Response Struct

// ContentLength records the length of the associated content. The
// value -1 indicates that the length is unknown. Unless Request.Method
// is "HEAD", values >= 0 indicate that the given number of bytes may
// be read from Body.
ContentLength int64