[DocDB] Eliminate the need for explicit aggressive poll interval - wait_queue_poll_interval_ms for contentious workloads

[robertsami]

Jira Link: DB-5848

Description

We currently depend on a polling-based approach to resolve waiting transactions in the wait queue in order to achieve fairness under highly-contentious workloads, e.g. a workload where 10s of sessions are concurrently locking the same row.

Without aggressive polling (e.g. setting wait_queue_poll_interval_ms=5), such highly contentious workloads will suffer from high p99 latencies

Once we have #13578, we should ensure that highly contentious workloads can function with predictable p99 performance even with wait_queue_poll_interval_ms=100 or larger. Otherwise, we are trading off significant CPU overhead for fairness

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[robertsami]

for example, with the following transaction:

begin;
select * from foo where k = 1 for update;
commit;

if we have a single node local cluster on a 6 core machine, and we run this in 8 parallel threads, we will see something like 1/1000 requests experience 100x avg latency