changes in Telemetry Frontend service and client.

- collector description is removed from TelemetryModel.
- "ConvertCollectorToRow" is added in Telemetry Model class.
- NameMapping is removed from service client and service.
- TelemetryDB object name and import is updated with correct class name.
- StartCollector is restructured.
- "PublishRequestOnKafka" is restructured.