DATAGRAPH-323 total elements count fix

The count query should always be executed, even when the returned element number is smaller than the page size.

E.g. imagine 3 results when the page size is 2
- The first page would return 2 elements and a total element count of 3 => OK
- The second page would return 1 element and a total element count of 1 => should also be 3!

Does this seem correct or am I missing something conceptually?