Specify a smaller concurrencyKey concurrency limit

This would allow for being able to have a concurrency limit on the entire queue, lets say 10, but each concurrency key only gets lets say 1 at a time. So the queue would never been executing more than 10 at once, and each concurrency key would only ever execute 1 in parallel.

See this real world use-case: https://x.com/euboid/status/1929470623191101613