MB-8029 Remove old (partial) indexer code

This will not be needed anymore, as a different and more
complete approach will be in place soon.

Change-Id: Ib804c73c7c2053f2e0b8fab11d61a76dc6679097
Reviewed-on: http://review.couchbase.org/25635
Reviewed-by: Fulu Li <fulu@couchbase.com>
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>