Add smoketest for UC3 Flink

theodolite-benchmarks/docker-test/uc3-flink/test.sh

+#!/bin/sh
+
+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=s -r http://schema-registry:8081 -f '%k:%s\n' -c 600 |
+    tee /dev/stderr |
+    awk -F ':' '!/^%/ {print $1}' |
+    sort |
+    uniq |
+    wc -l |
+    grep "\b10\b"
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