Changes to telemetry service

- TelemetryBackendService name and port is added in constants
- get_kafka_address() call added in TelemetryBackendService
- kafk topics test added in telemetrybackend test file
- get_kafka_address() call added in TelemetryBackendServiceImpl
- kafk topics test added in telemetryfrontend test file
- improvements in Telemetry gitlab-ci file
   + unit_test for telemetry backend and frontend added.
   + many other small changes