This issue is tracking follow up work from the initial implementation of PartitionedRateLimiter in #67677.

• Figure out what interval to use for the internal Timer
  • Dynamically change it based on the intervals of the replenishing limiters?
  • Come up with some "good enough" default
  • Make it an option that the user must configure?
• Background exceptions are currently ignored and not visible to users
  • Check what other libraries like HttpClient do
  • Maybe ExceptionDispatchInfo.Capture and dispatch throwing to the threadpool so it's at least an unhandled exception
• Start using IdleDuration to cleanup internal dictionary when limiters aren't active
  • Probably don't want to immediately remove limiters when they become idle, likely should wait 10 seconds or something