checker, statistic: avoid leak in label statistic (#8703) #22155

Job	Run time
chunks (1, Unit Test(1))	4m 18s
chunks (1, Unit Test(1))	4m 14s
chunks (1, Unit Test(1))	5m 14s
chunks (1, Unit Test(1))	5m 14s
chunks (2, Unit Test(2))	3m 40s
chunks (2, Unit Test(2))	3m 40s
chunks (2, Unit Test(2))	3m 40s
chunks (2, Unit Test(2))	3m 40s
chunks (3, Unit Test(3))	4m 19s
chunks (3, Unit Test(3))	4m 14s
chunks (3, Unit Test(3))	4m 48s
chunks (3, Unit Test(3))	4m 48s
chunks (4, Tests(1))	4m 18s
chunks (4, Tests(1))	4m 15s
chunks (4, Tests(1))	10m 31s
chunks (4, Tests(1))	5m 52s
chunks (5, Tests(2))	4m 18s
chunks (5, Tests(2))	4m 14s
chunks (5, Tests(2))	5m 11s
chunks (5, Tests(2))	5m 11s
chunks (6, Tools Test)	4m 21s
chunks (6, Tools Test)	4m 16s
chunks (6, Tools Test)	6m 6s
chunks (6, Tools Test)	6m 6s
chunks (7, Client Integration Test)	4m 18s
chunks (7, Client Integration Test)	4m 13s
chunks (7, Client Integration Test)	5m 49s
chunks (7, Client Integration Test)	5m 49s
chunks (8, TSO Integration Test)	4m 19s
chunks (8, TSO Integration Test)	4m 13s
chunks (8, TSO Integration Test)	5m 17s
chunks (8, TSO Integration Test)	5m 17s
chunks (9, MicroService Integration(!TSO))	4m 4s
chunks (9, MicroService Integration(!TSO))	3m 58s
chunks (9, MicroService Integration(!TSO))	4m 4s
chunks (9, MicroService Integration(!TSO))	4m 4s
chunks (10, MicroService Integration(TSO))	4m 19s
chunks (10, MicroService Integration(TSO))	4m 15s
chunks (10, MicroService Integration(TSO))	5m 46s
chunks (10, MicroService Integration(TSO))	5m 46s
report-coverage	0s
report-coverage	0s
report-coverage	0s
report-coverage	36s
	3h 12m 35s

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