Add more protection in QuicSpdySession::GetSpdyDataStream().
Add more protection in QuicSpdySession::GetSpdyDataStream().

From the definition of GetOrCreateDynamicStream(), it's possible that the returned stream is a static non-spdy stream.
So instead of using DCHECK as invariants, I think it'd be better if we close connection here.

gfe-relnote: Protected by gfe2_reloadable_flag_quic_handle_staticness_when_getting_spdy_stream
PiperOrigin-RevId: 257486450
Change-Id: I7ac6c4b6f9e78ff263ee0937c647bbfb35de4e22

google/quiche,google/quiche,google/quiche,google/quiche