[v4.4 only] an index catalog entry may not have an ident on startup recovery when running with majority read concern off and repl two-phase drop

In v4.4 with majority read concern off, we use repl two-phase drop to rename a collection out of the way and then drop it when the drop timestamp is majority committed. If there is a checkpoint taken between starting an index build and dropping the collection+index wt tables for majority confirmed drop, startup recovery will have the index catalog entry and no index table. In standalone recovery mode, we skip restarting index builds, leaving the server in a state wherein we have an index catalog entry and no index table. Then, later, we try to instantiate a WiredTigerIndex instance on the non-existent index table.