Revert "SERVER-12662 do not logOp inserts that have no associated diskloc (such as index-already-exists)"

This reverts commit 2f3bd6fc8f3b50bf4802f4477c55660355cff9fe.
The commit does not work for _id index builds and will require a more comprehensive solution.
Merge remote-tracking branch 'upstream/v2.4' into v2.4