Fix deletion visibility in region migration IT #30004

Job	Run time
unit-test (17, ubuntu-latest, datanode)	30m 5s
unit-test (17, windows-latest, others)	20m 36s
unit-test (17, ubuntu-latest, others)	15m 51s
unit-test (17, windows-latest, datanode)	42m 37s
	1h 49m 9s

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