Sustained attempts per second.
OptionalburstBucket size: attempts that may go out back to back after a quiet spell.
OptionalmaxLongest an attempt may wait for its token. An attempt that would wait
longer fails at once with RateLimitedError. Omit to wait as long as
needed, bounded only by cancel() and timeout.totalMs.
Token-bucket rate limit per partition. Every attempt, first attempts and retries alike, takes a token before it is sent, waiting for one when the bucket is empty. Bulkheads cap concurrency; this caps rate. Opt-in: no limit applies unless one is configured.