add batcher config to splunkhec exporter (#32563) #2

Job	Run time
windows-unittest-matrix (receiver-0)	17m 41s
windows-unittest-matrix (receiver-1)	22m 32s
windows-unittest-matrix (receiver-2)	16m 26s
windows-unittest-matrix (receiver-3)	20m 47s
windows-unittest-matrix (processor-0)	14m 27s
windows-unittest-matrix (processor-1)	14m 0s
windows-unittest-matrix (exporter-0)	14m 5s
windows-unittest-matrix (exporter-1)	18m 30s
windows-unittest-matrix (exporter-2)	13m 36s
windows-unittest-matrix (exporter-3)	16m 50s
windows-unittest-matrix (extension)	14m 59s
windows-unittest-matrix (connector)	14m 34s
windows-unittest-matrix (internal)	18m 39s
windows-unittest-matrix (pkg)	11m 18s
windows-unittest-matrix (cmd-0)	16m 1s
windows-unittest-matrix (cmd-1)	15m 26s
windows-unittest-matrix (other)	24m 50s
windows-unittest	3s
	4h 44m 44s

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