Unlike

• ShardLocal::_exhaustiveFindOnConfig, which ensures read after opTime behavior by waiting for the last opTime for the Client to be committed
• ShardRemote::_exhaustiveFindOnConfig, which sends Grid's configOpTime in the readConcern of its requests to the config server
• ShardRemote::_runCommand, whose callers manually attach the Grid's configOpTime for read commands

ShardLocal::_runCommand does not do anything to ensure read after opTime.

This ticket is to separate the read after opTime behavior in ShardLocal::_exhaustiveFindOnConfig into an ensureReadAfterOpTime() function and call it in both ShardLocal::_exhaustiveFindOnConfig and ShardLocal::_runCommand.

This is to support moving metadata commands to the config server which use runCommand to do (non-cursor-generating) reads, such as counts.