Adapt offset scroll calculations to changes in Spring Data 2024.0

[rstoyanchev]

Spring Data 2024.0 will align offset with keyset scroll positions in spring-projects/spring-data-commons#3070 such that an offset position corresponds to the element index (i.e. no longer adding +1), and also for data store implementations to exclude rather than include the reference offset position.

This will require follow-up adjustments on our end. For forward pagination we no longer need to advance by 1. For backward pagination, we need to advance back by (count + 1) so the results exclude the reference position.