Combine deleteArchived{Files,Revisions}.inc into the .php scripts

Combine deleteArchived{Files,Revisions}.inc into the .php scripts

Some of deleteArchivedFiles.php and deleteArchivedRevisions.php were
split off to deleteArchivedFiles.inc and deleteArchivedRevisions.inc
respectively in r62948 (04b2413aacfd) for use in tests.

The tests no longer use those methods, so I moved them back and inlined
them into execute(). I also did some minor cleanup -- changing direct
calls to tableName() and query() to use query builder functions and
clarifying/fixing some of the logic that was in deleteArchivedFiles.inc.

Change-Id: Ica49dcac18a9c702cffe02e562c6dff48d2d2784