Remove QuicSession::RegisterStaticStream() and merge it into
QuicSession::ActivateStream().

As static_stream_map_ has been removed, static streams are getting less and
less distinct from normal streams. And now after preventing
v99_stream_id_manager from knowing about stream staticness, static streams are
all the same as dynamic streams only to be different in is_static_ field.

So I think it'd be a nice cleanup to have only one method.

gfe-relnote: code refactoring. No behavior change.
PiperOrigin-RevId: 267652775
Change-Id: I27137a225c69c0a41c644d473d59e7a4c3c64359
diff --git a/quic/qbone/qbone_server_session.cc b/quic/qbone/qbone_server_session.cc
index 37cdd4c..49f84eb 100644
--- a/quic/qbone/qbone_server_session.cc
+++ b/quic/qbone/qbone_server_session.cc
@@ -59,7 +59,7 @@
   auto control_stream =
       QuicMakeUnique<QboneServerControlStream>(this, handler_);
   control_stream_ = control_stream.get();
-  RegisterStaticStream(std::move(control_stream));
+  ActivateStream(std::move(control_stream));
 }
 
 bool QboneServerSession::SendClientRequest(const QboneClientRequest& request) {