The space/time complexity can be improved in `RateLimiterFilterInput` gRPC query

[ws4charlie]

Describe the Issue It's needed probably only when we have heavy traffic of pending cctxs across all chains. Let's see. Given a limit number of cctxs, there is room to improve the algorithm (both space and time) of getting all pending cctxs order by height in the gRPC query RateLimiterInput.

Expected Outcome A description of what outcome you are seeking.