Increase client timeout and disable queue timeout for conformance tests

Summary:
Fix flaky Erlang Thrift conformance tests (`fbcode//thrift/conformance/test/rpc/erlang:rpc-client-test`) which have 75-95% flakiness rates due to two issues:

1. Client timeout too short: The Erlang BEAM VM, started via a dotslash/MSDK binary, takes longer than 10 seconds to boot in Sandcastle CI. This causes the test harness to give up before the client connects. Increase the non-sanitizer kClientTimeout from 10s to 30s. Passing tests complete in 1.5-3s, so 30s gives plenty of margin.

2. Queue timeout triggering load shedding: The conformance test server default 100ms queue timeout rejects the Erlang client RPC with a load shedding error (QUEUE_TIMEOUT). Disable queue timeout in the test server by calling server.setQueueTimeout(std::chrono::milliseconds(0)) - test environments should never reject clients due to load shedding.

Reviewed By: iahs

Differential Revision: D109872927

fbshipit-source-id: 9020e2934edfbe427ae29a763c685b2dd43cd147

Author: jpaton

thrift/conformance/rpcclient/GTestHarnessRPCClient.cpp

@@ -26,7 +26,7 @@
     __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)
 constexpr auto kClientTimeout = std::chrono::seconds(60);
 #else
-constexpr auto kClientTimeout = std::chrono::seconds(10);
+constexpr auto kClientTimeout = std::chrono::seconds(30);
 #endif
 
 #include <fmt/core.h>
@@ -588,6 +588,10 @@ class RPCClientConformanceTest : public testing::Test {
                   if (connectViaServer) {
                     std::ignore = update_server_props_(server);
                   }
+                  // Disable queue timeout for conformance tests. Test clients
+                  // (especially Erlang/BEAM VM) may be slow to start and should
+                  // never be rejected by load shedding in a test environment.
+                  server.setQueueTimeout(std::chrono::milliseconds(0));
                 })),
         connectViaServer_(connectViaServer) {
     try {