Remove combineCommonParents function which does nothing #1049

Job	Run time
cpp-lib-build (macos-11, clang, ON)	10m 52s
cpp-lib-build (macos-11, clang, OFF)	10m 27s
build (macos-11, tool)	2m 12s
cpp-lib-build (macos-11, gcc, ON)	9m 50s
build (macos-11, cpp)	45m 28s
cpp-lib-build (macos-11, gcc, OFF)	13m 13s
build (macos-11, csharp)	14m 3s
cpp-lib-build (ubuntu-20.04, clang, ON)	3m 33s
build (macos-11, dart)	10m 1s
cpp-lib-build (ubuntu-20.04, clang, OFF)	3m 25s
build (macos-11, go)	6m 25s
build (macos-11, java)	4m 7s
cpp-lib-build (ubuntu-20.04, gcc, ON)	4m 59s
build (macos-11, javascript)	3m 18s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	5m 9s
build (macos-11, typescript)	26m 14s
cpp-lib-build (windows-2022, clang, ON)	4m 8s
build (macos-11, php)	24s
cpp-lib-build (windows-2022, clang, OFF)	5m 25s
cpp-lib-build (windows-2022, cl)	4m 49s
build (macos-11, python3)	2m 20s
build (ubuntu-20.04, tool)	1m 5s
build (ubuntu-20.04, cpp)	17m 44s
build (ubuntu-20.04, csharp)	5m 5s
build (ubuntu-20.04, dart)	3m 54s
build (ubuntu-20.04, go)	2m 33s
build (ubuntu-20.04, java)	1m 17s
build (ubuntu-20.04, javascript)	1m 26s
build (ubuntu-20.04, typescript)	10m 6s
build (ubuntu-20.04, php)	1m 43s
build (ubuntu-20.04, python3)	1m 19s
build (windows-2022, tool)	1m 42s
build (windows-2022, cpp)	22m 15s
build (windows-2022, csharp)	7m 14s
build (windows-2022, dart)	4m 20s
build (windows-2022, go)	6m 35s
build (windows-2022, java)	1m 45s
build (windows-2022, javascript)	2m 19s
build (windows-2022, typescript)	20m 36s
build (windows-2022, php)	2m 16s
build (windows-2022, python3)	1m 42s
	5h 7m 18s

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