[Perf] Improve Performance of check_intervals

[bsbds]

For each txn request, we need to check if puts and deletes overlap. Deletes are range requests, and puts are single key requests, that we need to check for each key if it is in any of the delete ranges.

Current check_intervals is a naive approach that iterates through all delete ranges for each key, we could improve this by introducing the interval tree data structure.