Deprecate FLAGS_quic_disable_pre_30. Remove QUIC versions [25-29].

net/quic/quic_session.cc

Index: net/quic/quic_session.cc
diff --git a/net/quic/quic_session.cc b/net/quic/quic_session.cc
index 788cc68ba6ce643f776636bd2eb8970b07e734c4..15c437b52fad763dd392dd8aeae02cc0ac8e5fd8 100644
--- a/net/quic/quic_session.cc
+++ b/net/quic/quic_session.cc
@@ -701,14 +701,8 @@ ReliableQuicStream* QuicSession::GetOrCreateDynamicStream(
   // Check if the new number of open streams would cause the number of
   // open streams to exceed the limit.
   if (GetNumOpenIncomingStreams() >= max_open_incoming_streams()) {
-    if (connection()->version() <= QUIC_VERSION_27) {
-      connection()->CloseConnection(
-          QUIC_TOO_MANY_OPEN_STREAMS, "Old style stream rejection",
-          ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
-    } else {
-      // Refuse to open the stream.
-      SendRstStream(stream_id, QUIC_REFUSED_STREAM, 0);
-    }
+    // Refuse to open the stream.
+    SendRstStream(stream_id, QUIC_REFUSED_STREAM, 0);
     return nullptr;
   }