Improve resilience of some tests

Author: acogoluegnes

src/test/java/com/rabbitmq/client/test/functional/DeadLetterExchange.java

@@ -583,7 +583,7 @@ private void sleep(long millis) {
        publication time + TTL + latency */
     private void checkPromptArrival(QueueingConsumer c,
                                     int count, long latency) throws Exception {
-        long epsilon = TTL / 25;
+        long epsilon = TTL / 20;
         for (int i = 0; i < count; i++) {
             Delivery d = c.nextDelivery(TTL + TTL + latency + epsilon);
             assertNotNull("message #" + i + " did not expire", d);

src/test/java/com/rabbitmq/client/test/functional/TTLHandling.java

@@ -156,7 +156,7 @@ protected void releaseResources() throws IOException {
         closeChannel();
         openChannel();
 
-        Thread.sleep(150);
+        Thread.sleep(200);
         expectBodyAndRemainingMessages(MSG[1], 1);
         expectBodyAndRemainingMessages(MSG[2], 0);
     }