Fix reverse keyset scrolling

[mp911de]

Currently, we include the element at KeysetScrollPosition in the query via gte/lte. Using these operators with non-unique keys (e.g. firstName=John, age=41, id=1, firstName=John, age=41, id=2) with a query (firstName > John || firstName == John && age >= 41) includes potential duplicates that we're not able to remove from the final result.

We should resort to gt/lt instead of gte/lte.