fix flaky test

Summary: AsyncSocketSendmmsgIntegrationTest.PingPongRequest fails during stress runs with multiple jobs due to the 5ms timeout in `UDPClient::sendPing()`. Increasing the timeout fixes the issue.

Reviewed By: yfeldblum

Differential Revision: D29623870

fbshipit-source-id: ad6ee0356001fbded9ce01ddc099b708d1477899

folly/io/async/test/AsyncUDPSocketSendmmsgTest.cpp

@@ -217,7 +217,7 @@ class UDPClient : private AsyncUDPSocket::ReadCallback, private AsyncTimeout {
   }
 
   void sendPing() {
-    scheduleTimeout(5);
+    scheduleTimeout(50);
     auto bufs = testData_.getInBufs();
     writePing(bufs);
   }