[Telemetry docker] add memory and memory swap limits (sonic-net#7062)

#### Why I did it
Fix https://github.com/Azure/sonic-telemetry/issues/71

#### How I did it
Added memory limit for telemetry docker.
Historical docker memory usage shows telemetry docker consuming 150-200MB memory. Adding some extra buffer.

rules/docker-telemetry.mk

@@ -29,6 +29,7 @@ endif
 
 $(DOCKER_TELEMETRY)_CONTAINER_NAME = telemetry
 $(DOCKER_TELEMETRY)_RUN_OPT += --privileged -t
+$(DOCKER_TELEMETRY)_RUN_OPT += --memory 500m
 $(DOCKER_TELEMETRY)_RUN_OPT += -v /etc/sonic:/etc/sonic:ro
 $(DOCKER_TELEMETRY)_RUN_OPT += -v /usr/share/sonic/scripts:/usr/share/sonic/scripts:ro
 $(DOCKER_TELEMETRY)_RUN_OPT += -v /var/run/dbus:/var/run/dbus:rw