Try to use the index even if the query matches all entries

A DSL query with no filter clauses will match all entries. In this case we currently run a non-indexed query even if the cache is indexed. This is ok for queries that do not use sorting or projections. In that case we do not get any benefit from involving the index because we'll fetch all entries anyway.

Performance can be improved by using the index if the query has sorting or projections so this should be treated as a special case.