Fix sonar issue in GroupByMemoryMergedResult #12602

Job	Run time
Import Global Environment / init-environment	4s
Build E2E Image	8m 34s
E2E - Agent with MySQL (proxy, tracing, jaeger)	6m 57s
E2E - Agent with MySQL (proxy, tracing, zipkin)	7m 12s
E2E - Agent with MySQL (proxy, metrics, prometheus)	7m 18s
E2E - Agent with MySQL (proxy, logging, file)	6m 52s
E2E - Agent with MySQL (jdbc, logging, file)	7m 6s
E2E - Agent with MySQL (jdbc, metrics, prometheus)	6m 57s
E2E - Agent with MySQL (jdbc, tracing, jaeger)	6m 44s
E2E - Agent with MySQL (jdbc, tracing, zipkin)	6m 45s
	1h 4m 29s

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