This field is primarily intended to support avoiding displaying the
"more topics" feature in new organizations and streams, where we might
know that all messages in the stream are already available in the
browser.
Based on original work by Roman Godov, and significantly modified by
tabbott.
The second migration involved here could be expensive on Zulip Cloud,
but is unlikely to be an issue on other servers.
Challa Venkata Raghava Reddy