In SERVER-33609, setReadFromMajorityCommittedSnapshot() was refactored into two functions: setReadConcernLevelAndReplicationMode() and obtainMajorityCommittedSnapshot().

setReadConcernLevelAndReplicationMode() should be called to set the readConcern level in the recovery unit. It should be called at the early stage of an operation.

obtainMajorityCommittedSnapshot() is simply a function that refreshes the majorityCommittedSnapshot. It should only be called when we have "majority" or "snapshot" readConcern and replicationMode being modeReplSet.

However, while running some sharding tests, in rs_local_client's queryOnce function, we could have readConcernLevel being "majority' while replicationMode being none (standalone node). I fixed those tests by manually setting the replicationMode to be replSet so we can call obtainMajorityCommittedSnapshot(). Another potential fix might be ignoring the standalone case? I am not sure what this function really wants here so I am creating this ticket for further fixes.