[MINOR] tcp_request: let the caller take care of errors and timeouts

[MINOR] tcp_request: let the caller take care of errors and timeouts

tcp_request is not meant to decide how an error or a timeout has to
be handled. It must just apply it rules. Now that the error checks
have been added to the session, we don't need to check them anymore
in tcp_request_inspect(), which will only consider the shutdown which
may be the result of such an error.

That makes a lot more sense since tcp_request is not really waiting
for a request.