Handle lack of "sleepiness" in web and background workers

[ankush]

1. RQ's pubsub thread wakes up very aggressively (every 0.2s): [perf] possible to increase sleep_time for pubsub thread? rq/rq#2170
2. Gunicorn's threaded worker aggressively wakes up (every 1s): perf(gthread): reduce unnecessary polling benoitc/gunicorn#3319

Either get it improved upstream or override in our code.

[ankush]

There's still some more stuff in worker-pool, though possibly unavoidable.

Scheduler can be disabled by us though.

[ankush]

frappe/frappe#29127

[ankush]

It's not "done" yet, but closing it since eventually it will be fixed in our codebase.