Faster count queries when updating the info about current node

Faster count queries when updating the info about current node

MySQL optimiser seems to prefer a full table scan of `post-user`
table in the count query mentioned in issue #14763. When the origin
and deleted columns are added to the index, the IN-query part of
the query can be done with index-only scan, which is much faster.

Adding the columns in the order

    uri-id, origin, deleted

allows some other queries to also use it when checking
for uri-id and origin.

Fixes #14763