Unify `par_dispatch`, `par_for_outer` & `par_for_inner` overloads #5482

Job	Run time
CI-Rocm-HIP (hipcc, Release, hip, serial)	40m 9s
CI-Cuda-Host (g++, Release, cuda, serial)	49m 49s
CI-Rocm-HIP (hipcc, Release, hip, mpi)	45m 40s
CI-Cuda-Host (g++, Release, cuda, mpi)	48m 17s
CI-Rocm-HIP (hipcc, Debug, hip, serial)	1h 8m 53s
CI-Cuda-Host (g++, Release, host, serial)	14m 30s
CI-Rocm-HIP (hipcc, Debug, hip, mpi)	1h 6m 51s
CI-Cuda-Host (g++, Release, host, mpi)	14m 49s
CI-Cuda-Host (g++, Debug, cuda, serial)	1h 47m 36s
CI-Cuda-Host (g++, Debug, cuda, mpi)	1h 45m 47s
CI-Cuda-Host (g++, Debug, host, serial)	12m 26s
CI-Cuda-Host (g++, Debug, host, mpi)	13m 33s
CI-Cuda-Host (clang++-15, Release, cuda, serial)	31m 45s
CI-Cuda-Host (clang++-15, Release, cuda, mpi)	32m 22s
CI-Cuda-Host (clang++-15, Release, host, serial)	12m 41s
CI-Cuda-Host (clang++-15, Release, host, mpi)	12m 23s
CI-Cuda-Host (clang++-15, Debug, host, serial)	8m 53s
CI-Cuda-Host (clang++-15, Debug, host, mpi)	9m 14s
	11h 35m 38s

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