Make smaller workloads for scheduler_perf integration tests

Author: macsko

test/integration/scheduler_perf/README.md

@@ -113,3 +113,6 @@ Integration testing uses the same `config/performance-config.yaml` as
 benchmarking. By default, workloads labeled as `integration-test` are executed
 as part of integration testing. `-test-scheduling-label-filter` can be used to
 change that.
+
+We should make each test case with `integration-test` label very small,
+so that all tests with the label should take less than 5 min to complete.