Fix default batcher to correctly call all done callbacks exactly once #31334

Job	Run time
contrib-tests-matrix (receiver-0)	3m 29s
contrib-tests-matrix (receiver-1)	3m 29s
contrib-tests-matrix (receiver-2)	3m 30s
contrib-tests-matrix (receiver-3)	3m 29s
contrib-tests-matrix (processor)	3m 29s
contrib-tests-matrix (exporter-0)	3m 15s
contrib-tests-matrix (exporter-1)	3m 30s
contrib-tests-matrix (extension)	3m 30s
contrib-tests-matrix (connector)	3m 31s
contrib-tests-matrix (internal)	3m 31s
contrib-tests-matrix (pkg)	3m 30s
contrib-tests-matrix (cmd-0)	43s
contrib-tests-matrix (cmd-1)	1m 25s
contrib-tests-matrix (other)	3m 31s
contrib_tests	1s
	43m 53s

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