WikiPage: Avoid locking comment and actor tables in doDeleteArticleReal

WikiPage: Avoid locking comment and actor tables in doDeleteArticleReal

The existing code was using FOR UPDATE when selecting the revision table
rows to be added to the archive table, which meant it was locking not
only `revision`, `revision_comment_temp`, and `revision_actor_temp` that
are being updated but also `comment` and `actor` that we have no
intention of touching. And since those both are intended to be widely
shared, that's likely to lead to unnecessary lock contention.

To avoid that, we make two queries: one against only the rows we want to
lock with FOR UPDATE, and the second to actually fetch the data without
FOR UPDATE.

Bug: T191892
Change-Id: I40ecf1786249c886a5ff25f29ec01edee3ff205d