populate_db: Don't mark messages as read for bot users.
populate_db: Don't mark messages as read for bot users.

Bots don't generally do API requests to mark messages as read. If they
did, it's likely because the developer of the bot wants them to appear
in read receipts or similar (E.g. as an indication of what messages
have been processed).

So we should avoid setting the read flag on bot messages the test
database.

rht/zulip,rht/zulip,zulip/zulip,zulip/zulip,andersk/zulip,rht/zulip,zulip/zulip,zulip/zulip,zulip/zulip,rht/zulip,rht/zulip,zulip/zulip,andersk/zulip,andersk/zulip,andersk/zulip,andersk/zulip,zulip/zulip,rht/zulip,andersk/zulip,rht/zulip,andersk/zulip