Add a test to reproduce envoy crash at rds update

[qiwzhang]

Signed-off-by: Wayne Zhang qiwzhang@google.com

Description: Add an ADS integration test to reproduce crash reported in #3953

Risk Level: None

Testing: Integration test.

It crashes with same back trace:

223c Envoy::Router::RdsRouteConfigProviderImpl::onConfigUpdate()
deff6 Envoy::Config::GrpcMuxSubscriptionImpl<>::onConfigUpdate()
379df Envoy::Config::GrpcMuxImpl::onReceiveMessage()
3e3ab Envoy::Grpc::TypedAsyncStreamCallbacks<>::onReceiveMessageUntyped()
7db146 Envoy::Grpc::AsyncStreamImpl::onData()
7dff30 Envoy::Http::AsyncStreamImpl::encodeData()
d5e685 Envoy::Router::Filter::onUpstreamData()
d5ffc8 Envoy::Router::Filter::UpstreamRequest::decodeData()
7c55ce Envoy::Http::StreamDecoderWrapper::decodeData()
e1391f Envoy::Http::Http2::ConnectionImpl::onFrameReceived()
e1556c Envoy::Http::Http2::ConnectionImpl::Http2Callbacks::Http2Callbacks()::{lambda()#6}::operator()()
e1559c Envoy::Http::Http2::ConnectionImpl::Http2Callbacks::Http2Callbacks()::{lambda()#6}::_FUN()
e22656 nghttp2_session_on_data_received
e26771 nghttp2_session_mem_recv
e12848 Envoy::Http::Http2::ConnectionImpl::dispatch()
dfbeba Envoy::Http::CodecClient::onData()
dfd59b Envoy::Http::CodecClient::CodecReadFilter::onData()
5fe3e4 Envoy::Network::FilterManagerImpl::onContinueReading()
5fe4f8 Envoy::Network::FilterManagerImpl::onRead()
5f3734 Envoy::Network::ConnectionImpl::onRead()
5f4dba Envoy::Network::ConnectionImpl::onReadReady()
5f4b60 Envoy::Network::ConnectionImpl::onFileEvent()
5f18fa Envoy::Network::ConnectionImpl::ConnectionImpl()::{lambda()#3}::operator()()
5f693f std::_Function_handler<>::_M_invoke()
5e7d7d std::function<>::operator()()
5e6d2e Envoy::Event::FileEventImpl::assignEvents()::{lambda()#1}::operator()()
5e6dad Envoy::Event::FileEventImpl::assignEvents()::{lambda()#1}::_FUN()
14f1db4 event_process_active_single_queue.isra.29
14f24fe event_process_active
14f5287 event_base_loop
5e1b4d Envoy::Event::DispatcherImpl::run()
553357 Envoy::Server::InstanceImpl::run()
52471d Envoy::IntegrationTestServer::threadRoutine()
523a64 Envoy::IntegrationTestServer::start()::{lambda()#1}::operator()()
524ab3 std::_Function_handler<>::_M_invoke()
4e7079 std::function<>::operator()()
12519fb Envoy::Thread::Thread::Thread()::{lambda()#1}::operator()()
1251a20 Envoy::Thread::Thread::Thread()::{lambda()#1}::_FUN()

[mattklein123]

Going to close this. @lizan please merge the test into your other PR if you didn't already?