[mdatagen] bug fix - reaggreagate_set test generation (#14441) #32336

Job	Run time
windows-service-test (windows-11-arm)	3m 37s
windows-unittest (windows-11-arm)	11m 12s
windows-unittest (windows-2025)	18m 22s
windows-service-test (windows-2022)	2m 56s
windows-service-test (windows-2025)	3m 21s
windows-unittest (windows-2022)	16m 37s
	56m 5s

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