Fix quick pulse disabled option (#1824)

* Fix quick pulse disabled option

* Fix test logging

Author: trask

agent/agent-tooling/src/main/java/com/microsoft/applicationinsights/agent/internal/quickpulse/QuickPulseDataCollector.java

@@ -176,6 +176,11 @@ synchronized FinalCounters peek() {
   }
 
   public void add(TelemetryItem telemetryItem) {
+    if (telemetryClient == null) {
+      // quick pulse is not enabled
+      return;
+    }
+
     if (!telemetryItem.getInstrumentationKey().equals(getInstrumentationKey())) {
       return;
     }