Fix Multigrid Solver in Forest #3951

Job	Run time
CI-Rocm-HIP (hipcc, Release, hip, serial)	29m 38s
CI-Cuda-Host (g++, Release, cuda, serial)	38m 7s
CI-Rocm-HIP (hipcc, Release, hip, mpi)	30m 8s
CI-Cuda-Host (g++, Release, cuda, mpi)	40m 19s
CI-Rocm-HIP (hipcc, Debug, hip, serial)	53m 15s
CI-Cuda-Host (g++, Release, host, serial)	10m 35s
CI-Rocm-HIP (hipcc, Debug, hip, mpi)	54m 23s
CI-Cuda-Host (g++, Release, host, mpi)	11m 18s
CI-Cuda-Host (g++, Debug, cuda, serial)	1h 5m 58s
CI-Cuda-Host (g++, Debug, cuda, mpi)	1h 8m 5s
CI-Cuda-Host (g++, Debug, host, serial)	9m 30s
CI-Cuda-Host (g++, Debug, host, mpi)	9m 54s
CI-Cuda-Host (clang++-15, Release, cuda, serial)	24m 26s
CI-Cuda-Host (clang++-15, Release, cuda, mpi)	23m 21s
CI-Cuda-Host (clang++-15, Release, host, serial)	9m 12s
CI-Cuda-Host (clang++-15, Release, host, mpi)	9m 14s
CI-Cuda-Host (clang++-15, Debug, host, serial)	7m 19s
CI-Cuda-Host (clang++-15, Debug, host, mpi)	7m 6s
	8h 21m 48s

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