Reduce experiment smoketest time for UC4/Samza

theodolite-benchmarks/docker-test/uc4-beam-samza/test.sh

@@ -2,7 +2,7 @@
 
 until docker-compose exec -T kcat kcat -L -b kafka:9092 -t output -J | jq -r '.topics[0].partitions | length' | grep "\b3\b"; do sleep 5s; done
 
-docker-compose exec -T kcat kcat -C -b kafka:9092 -t output -s key=s -s value=avro -r http://schema-registry:8081 -f '%k:%s\n' -c 2000 |
+docker-compose exec -T kcat kcat -C -b kafka:9092 -t output -s key=s -s value=avro -r http://schema-registry:8081 -f '%k:%s\n' -c 300 |
     tee /dev/stderr |
     awk -F ':' '!/^%/ {print $1}' |
     sort |