MINOR: quic: ignore uni-stream for initial max data TP

MINOR: quic: ignore uni-stream for initial max data TP

Initial TP value for max-data is automatically calculated to be adjusted
to the maximum number of opened streams over a QUIC connection. This
took into account both max-streams-bidi-remote and uni-streams. By
default, this is equivalent to 100 + 3 = 103 max opened streams.

This patch simplifies the calculation by only using bidirectional
streams. Uni streams are ignored because they are only used for HTTP/3
control exchanges, which should only represents a few bytes. For now,
users can only configure the max number of remote bidi streams, so the
simplified calculation should make more sense to them.

Note that this relies on the assumption that HTTP/3 is used as
application protocol. To support other protocols, it may be necessary to
review this and take into account both local bidi and uni streams.