Fix the unit of the interval of default-observer in the log (#1193)

Signed-off-by: Justin Yang <justin.yang@themedium.io>

Author: justin-themedium

packages/caliper-core/lib/manager/test-observers/default-observer.js

@@ -34,7 +34,7 @@ class DefaultObserver extends TestObserverInterface {
 
         // set the observer interval
         this.observeInterval = ConfigUtil.get(ConfigUtil.keys.Progress.Reporting.Interval);
-        Logger.info(`Observer interval set to ${this.observeInterval} seconds`);
+        Logger.info(`Observer interval set to ${this.observeInterval} milliseconds`);
         this.observeIntervalObject = null;
         this.updateTail = 0;
         this.updateID   = 0;