The maximum number of incoming streams doesn't need to be negotiated. It
is a value that is only announced by the peer, and has to be respected.
Furthermore, Chrome doesn't seem to care about the MSPC value anymore
(since MIDS was introduced), so there's no need to send this in the
handshake any more.
The params negotiator was just keeping track of the value set in the
quic.Config. The max flow control increments are not subject to
negotiation, but an independent implementation decision of every peer.
