Label MPC_NUM_REQUESTS_WITHOUT_REFINED_LEADER_TOTAL metric with chain

[anodar]

Background

We only label this per request type. Ideally we would also have chain label to see which chain is struggling specifically.

#4203 (comment)

User Story

No response

Acceptance Criteria

MPC_NUM_REQUESTS_WITHOUT_REFINED_LEADER_TOTAL metric has chain label.

Resources & Additional Notes

No response

[anodar]

Some of the (non-ideal) ways we can do this:

• add another method to Refiner trait that returns chain
• from refine method return chain as well
• Add method to Request itself (e.g. get_chain) that is option and only returns Some() for foreign chain requests