Stress test client service config (in kubernetes) need not be of 'LoadBalancers'

This fixes the GCP console slowness for grpc-testing project

Fixed the docker image building script to remove the "-f" option (that
is now deprecated) from 'docker tag' command.

tools/run_tests/dockerize/build_interop_stress_image.sh

@@ -98,7 +98,7 @@ CONTAINER_NAME="build_${BASE_NAME}_$(uuidgen)"
   $BASE_IMAGE \
   bash -l /var/local/jenkins/grpc/tools/dockerfile/stress_test/$BASE_NAME/build_interop_stress.sh \
   && docker commit $CONTAINER_NAME $INTEROP_IMAGE \
-  && ( if [ -n "$INTEROP_IMAGE_REPOSITORY_TAG" ]; then docker tag -f $INTEROP_IMAGE $INTEROP_IMAGE_REPOSITORY_TAG ; fi ) \
+  && ( if [ -n "$INTEROP_IMAGE_REPOSITORY_TAG" ]; then docker tag $INTEROP_IMAGE $INTEROP_IMAGE_REPOSITORY_TAG ; fi ) \
   && echo "Successfully built image $INTEROP_IMAGE")
 EXITCODE=$?
 

tools/run_tests/stress_test/cleanup_docker_images.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+for img in `docker images | grep \<none\> | awk '{print  $3 }'` ; do docker rmi -f $img; done
+

tools/run_tests/stress_test/run_on_gke.py

@@ -312,7 +312,7 @@ class Gke:
           [container_cmd],
           [],  # Empty args list since all args are passed via env variables
           client_env,
-          False  # Client is not a headless service.
+          True  # Client is a headless service (no need for an external ip)
       )
 
       if not is_success: