Dockerfile: Undo previous change (no need for --no-cache-dir since we're using a build container), clean up a little
Dockerfile: Undo previous change (no need for --no-cache-dir since we're using a build container), clean up a little

mbeacom/locust,mbeacom/locust,locustio/locust,mbeacom/locust,mbeacom/locust,locustio/locust,locustio/locust,locustio/locust