Refactor sequentialFlush at PipelineDataSourceSink of Pipeline #7495

Job	Run time
Import Global Environment / init-environment	4s
E2E - Agent with MySQL (proxy, tracing, jaeger)	8m 11s
E2E - Agent with MySQL (proxy, tracing, zipkin)	8m 38s
E2E - Agent with MySQL (proxy, metrics, prometheus)	10m 15s
E2E - Agent with MySQL (proxy, logging, file)	10m 55s
E2E - Agent with MySQL (jdbc, logging, file)	8m 39s
E2E - Agent with MySQL (jdbc, metrics, prometheus)	8m 39s
E2E - Agent with MySQL (jdbc, tracing, jaeger)	9m 15s
E2E - Agent with MySQL (jdbc, tracing, zipkin)	9m 4s
	1h 13m 40s

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