Remove test delays (#5579)

* Changing __indexBuildCompletionCallbackForTests callback to serverStartComplete

* Improving serverStartComplete callback to avoid production unhandled promise rejection

* Add test to check inexistence of unhandled promise rejection on server fail

* Removing some hooks delays

* Removing delay after reconfigureServer

* Improving code style

spec/helper.js

@@ -150,10 +150,13 @@ const reconfigureServer = changedConfiguration => {
         defaultConfiguration,
         changedConfiguration,
         {
-          __indexBuildCompletionCallbackForTests: indexBuildPromise =>
-            indexBuildPromise.then(() => {
+          serverStartComplete: error => {
+            if (error) {
+              reject(error);
+            } else {
               resolve(parseServer);
-            }, reject),
+            }
+          },
           mountPath: '/1',
           port,
         }