Force primary index for RevDelRevisionList query

Force primary index for RevDelRevisionList query

To work around an optimizer bug in MySQL where the
index on (rev_page, rev_id) is picked which mysteriously
leads to very slow execution times and timeouts.

In theory, the index being forced here is (rev_id),
which is fine for this query. In WMF production,
it can also be (rev_id, rev_user) (still fine), or
(rev_page, rev_id) (the index we're trying to avoid).
Mysteriously, the optimizer bug doesn't happen if
(rev_page, rev_id) is the primary key, so this still
behaves OK.

Bug: T104313
Change-Id: I15c68ba29309dca8dea274f19389d139a82784aa