perf(ci): calibrate webapp shards with CI timings

Author: carderne

.github/workflows/unit-tests-webapp.yml

@@ -23,7 +23,8 @@ jobs:
       # one flaky shard shouldn't cancel its siblings - lets us re-run only the failed shard
       fail-fast: false
       matrix:
-        shardIndex: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
+        shardIndex:
+          [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
         shardTotal: [24]
     env:
       DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}