[receiver/tcplog] remove `SplitFuncBuilder` from mapstructure (#39485) #19

Job	Run time
darwin-build-unittest-binary (macos-14)	5m 32s
darwin-build-unittest-binary (macos-15)	5m 48s
darwin-unittest-matrix (macos-13)	2m 5s
darwin-unittest	1s
	13m 26s

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