Add default version for QuicTransport and use it in all unit tests.

This currently uses draft25, as draft27 doesn't yet has a quic_verions codepoint.

gfe-relnote: n/a (not used in production)
PiperOrigin-RevId: 298468043
Change-Id: I5dfd78a05717f166c56092b0ca3d868afb257072
diff --git a/quic/quic_transport/quic_transport_stream_test.cc b/quic/quic_transport/quic_transport_stream_test.cc
index 3c92101..6a91702 100644
--- a/quic/quic_transport/quic_transport_stream_test.cc
+++ b/quic/quic_transport/quic_transport_stream_test.cc
@@ -24,15 +24,7 @@
 using testing::Return;
 
 ParsedQuicVersionVector GetVersions() {
-  for (const ParsedQuicVersion& version : AllSupportedVersions()) {
-    // Find the first version that supports IETF QUIC.
-    if (version.HasIetfQuicFrames() &&
-        version.handshake_protocol == quic::PROTOCOL_TLS1_3) {
-      return {version};
-    }
-  }
-  CHECK(false);
-  return {};
+  return {DefaultVersionForQuicTransport()};
 }
 
 class MockQuicTransportSessionInterface : public QuicTransportSessionInterface {
@@ -48,6 +40,7 @@
                                            Perspective::IS_CLIENT,
                                            GetVersions())),
         session_(connection_) {
+    QuicEnableVersion(DefaultVersionForQuicTransport());
     session_.Initialize();
 
     stream_ = new QuicTransportStream(0, &session_, &interface_);