Improve diagnostics related to rate limiting so people not disable it

## Summary

When enabling rate limiting, people start getting exceptions and warnings, which they misinterpret and end up disabling the rate limiting in Kestrel.

### People with more context
@halter73, @davidfowl, @jkotalik, @ajaybhargavb

## Motivation and goals

1-2 paragraphs, or a bullet-pointed list. What existing pain points does this solve? What evidence shows it's valuable to solve this?

## In scope

A list of major scenarios, perhaps in priority order.

## Out of scope

Scenarios you explicitly want to exclude.

## Risks / unknowns

How might developers misinterpret/misuse this? How might implementing it restrict us from other enhancements in the future? Also list any perf/security/correctness concerns.

## Examples

Give brief examples of possible developer experiences (e.g., code they would write).

Don't be deeply concerned with how it would be implemented yet. Your examples could even be from other technology stacks.