Decrease load on qq deployment

It still puts a significant load on the host, but any lower and we won't
see any change in the Uncommited log entries graph, and too little
variation in the Log entry commit latency.

deps/rabbitmq_prometheus/docker/docker-compose-qq.yml

@@ -46,7 +46,7 @@ services:
       - "5681:5672"
       - "15681:15672"
       - "15701:15692"
-  stress-qq:
+  qq-moderate-load:
     image: &perf-test-image pivotalrabbitmq/perf-test:2.9.1-ubuntu
     networks:
       - "rabbitmq-prometheus"
@@ -60,7 +60,7 @@ services:
       QUEUE_ARGS: x-queue-type=quorum,x-max-length=1000
       FLAG: persistent
       AUTO_DELETE: "false"
-      RATE: 200
+      RATE: 50
       AUTOACK: "false"
       SERVERS_STARTUP_TIMEOUT: &startup_timeout 30
       METRICS_PROMETHEUS: "true"