In COMPASS-6712, we hid collections stats for time series collections because they weren't being populated correctly, and it was simpler at the time to hide the stats instead of surfacing them. However, we should do the work to get the stats to show up correctly for Documents, Avg. document size, Indexes, and Total index size (today, only Storage size shows up).

After speaking with michael.gargiulo@mongodb.com , it sounds like the best path forward would be to add Index stats (Indexes and Total index size) and bucket stats (Avg. bucket size and Bucket count). These terms should hopefully be understood by time series collection users, as they're mentioned in our docs more and more. Documents and Avg. document size are not present in the $collStats output for time series collections, and it would be confusing to these users if we attempt to derive them.