[dst] Improve metrics collection related-to pessimistic locking

[robertsami]

Jira Link: DB-3160 Some examples:

1. latency of deadlock detection (min, max, avg)
2. avg cycle length in deadlock detection
3. deadlocks detected per second
4. wait time in wait queue
5. number of blockers for a waiter (min, max, avg)
6. number of waiters for a blocker (min, max, avg)

More TBD

Ensure also that memory usage of deadlock_detector and wait_queue are captured by mem tracker