MB-8582: Move ETS table names to indexer specific module

Change-Id: I97609184562b3fa0dab4dd318a3bc2e5d4838160
Reviewed-on: http://review.couchbase.org/27609
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: buildbot <build@couchbase.com>