Followup to #8731: use isSplittedVarDeclEq() (#8739) #20426

Job	Run time
build_cmake (ubuntu:24.04, true, true)	3m 22s
build_cmake (alpine:3.23, false, false)	2m 50s
build_cmake (ubuntu:25.10, true, true)	3m 6s
build_make (ubuntu:25.10)	3m 41s
build_make (alpine:3.23)	6m 24s
build_make (ubuntu:24.04)	3m 5s
	22m 28s

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