Don't estimate the revision count for page deletions

Don't estimate the revision count for page deletions

Often the estimated revision count is several thousands away
from the real one, thus disallowing normal sysops to delete
pages which they actually should be able to delete.

This also changes the revision number shown to users on
action=delete to the real one, as that code path is only
being hit for users that can delete the page.

Bug: 69556
Change-Id: Id0d02aa9960477a0cec8752ef714b6bc6b9ff2ac