We have various indexes on the namespaces field on config.collections thus we should be able to get a list of sorted collections directly from the config server without the need of sorting them on the shard.

https://github.com/10gen/mongo/blob/1f1a391453abde32fe9e7c2537fff7b7de2cd2e0/src/mongo/db/s/shardsvr_check_metadata_consistency_participant_command.cpp#L121-L127

In order to achieve this we can add an additional optional paramter to ShardingCatalogClientImpl::getCollections to specify the sorting criteria.