Remove some syncs from MLMG #10009

Job	Run time
check_changes / check	3s
MSVC C++17 w/o Fortran w/o MPI	5m 1s
MSVC C++17 w/o Fortran w/o MPI static	6m 9s
MSVC Clang C++17 w/o Fortran w/o MPI	7m 2s
CUDA on Windows	6m 47s
	25m 2s

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