Fix build_deferred_indexes() for server versions < 6.5

In order prevent multiple network hops (one query to determine the list of deferred indexes and another query to build the deferred indexes), the following query was used to determine and build deferred indexes. However, older server versions do not seem to allow for a nested query to return a list of queries to build.

BUILD INDEX ON `bucketName` (

  (

    SELECT RAW name FROM system:indexes 

    WHERE (keyspace_id = "bucketName" AND bucket_id IS MISSING)

        AND state = "deferred"

  )

)

Fix:
Revert back to the 2 query method for older server versions. Keep the single query method for server versions (>= 6.5) that allow the nested query for building indexes.