Updates from review

Remove now out of scope changes to settings.
Rename some variables to go along with the rest of the rename.
Use a dedicated average class instead of tuples.
Update TODO with remaining question about default shard size.
Finish removing settings changes
Add class for shard size bucketing

Old way directly exposed multimaps which was harder to understand.  This
should be more clear.
Only enable ClusterInfo scanning if it is needed