add a delay for websocket registration

Author: BrandonArp

src/test/java/com/arpnetworking/metrics/mad/integration/TelemetryIT.java

@@ -82,6 +82,10 @@ public void testFromSamples() throws InterruptedException, ExecutionException, T
                     _statistic,
                     future::complete);
 
+            // Wait for subscription to be registered and align with aggregation period
+            Thread.sleep(1000);
+            sleepToBeginningOfSecond();
+
             try (Metrics metrics = METRICS_FACTORY.create()) {
                 for (int i = 1; i <= 10; ++i) {
                     for (int j = 1; j <= i; ++j) {
@@ -111,6 +115,8 @@ public void testFromAggregatedData() throws InterruptedException, ExecutionExcep
                     _statistic,
                     future::complete);
 
+            // Wait for subscription to be registered
+            Thread.sleep(1000);
             sleepToBeginningOfSecond();
 
             try (Metrics metrics = METRICS_FACTORY.create()) {
@@ -168,6 +174,8 @@ public void testFromMixedSamplesAndAggregatedData() throws InterruptedException,
                     _statistic,
                     future::complete);
 
+            // Wait for subscription to be registered
+            Thread.sleep(1000);
             sleepToBeginningOfSecond();
 
             // First mixed samples-aggregates unit of work