fixed dial transcribe is not able to receive final transcribe when closing the call (#1073)

* fixed dial transcribe is not able to received final transcribe when close call.

* wip

* fix review comment

* support call session delay detroy ep when current task is transcribe

* wip

* wip

* fixed review comments

* fixed review comments

lib/utils/helpers.js

@@ -0,0 +1,5 @@
+
+const sleepFor = (ms) => new Promise((resolve) => setTimeout(() => resolve(), ms));
+module.exports = {
+  sleepFor
+};