Fix missing private clauses in 3D viscous GPU loops #4561

Job	Run time
Lint Gate	1m 18s
Detect File Changes	11s
Github (ubuntu, mpi, debug, false)	2h 58m 30s
Github (ubuntu, no-mpi, single, no-debug, false)	28m 40s
Github (ubuntu, mpi, no-debug, false)	2h 15m 52s
Oak Ridge \| Frontier (gpu-omp)	1s
Oak Ridge \| Frontier (AMD) (cpu)	1s
Github (macos, mpi, no-debug, false)	1h 36m 0s
Georgia Tech \| Phoenix (gpu-acc)	1h 46m 59s
Oak Ridge \| Frontier (gpu-acc)	8h 11m 17s
Oak Ridge \| Frontier (AMD) (gpu-omp)	1s
Github (ubuntu, mpi, no-debug, true)	1h 34m 53s
Oak Ridge \| Frontier (cpu)	1s
Github (ubuntu, mpi, debug, true)	1h 56m 41s
Georgia Tech \| Phoenix (gpu-omp)	8h 11m 17s
Georgia Tech \| Phoenix (cpu)	1s
Github (macos, mpi, debug, false)	1h 12m 56s
	1d 6h 14m 39s

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