PM-2210 and PM-1452 linked cluster insert, update, delete, find, aggregate, getMore and bulkWrite commands into mongod. However, to differentiate between the corresponding mongod commands, the cluster commands currently are registered with the "cluster" prefix and exist under cluster_*_d.cpp. The difference between the commands in cluster_*_d.cpp and cluster_*_s.cpp is that the former require the internal privilege since prior to 8.0 they are only meant to be run in internal transactions. As part of introducing multiple command registries in PM-635, we should combine cluster_*_d.cpp and cluster_*_s.cpp and make sure that cluster commands on mongod require the same privileges as on mongos.