MPC node should not need to process blocks block events older than 200 blocks #2626
Description
Background
In theory, the MPC node should not care about block events (signature requests and responses), that are older than 200 blocks, as those already expired.
Ideally, we can save some resources.
User Story
Performance improvement are good for everyone.
Acceptance Criteria
The chain gateway crate takes a parameter delta and only starts streaming once its block header is in that range.
The mpc node automatically removes expired signature requests.
Resources & Additional Notes
No response