Handling timers for repeat dispute participation requests (#6901)

* Added participation and queue sizes metrics

* First draft of all metric code

* Tests pass

* Changed Metrics to field on participation + queues

* fmt

* Improving naming

* Refactor, placing timer in ParticipationRequest

* fmt

* Final cleanup

* Revert "Final cleanup"

This reverts commit 02e5608df64b2e0f7810905e4508673b2037d351.

* Changing metric names

* Implementing Eq only for unit tests

* fmt

* Removing Clone trait from ParticipationRequest

* fmt

* Moved clone functionality to tests helper

* fmt

* Fixing dropped timers on repeat requests

* Keep older best effort timers

* Removing comment redundency and explaining better

* Updating queue() to use single mem read

* fmt