Make the rabbit MQ queue name dynamic.

https://github.com/Evolutionary-Algorithms-On-Click/runner_controller_microservice/blob/6e10ff11c80ffa44c2b0f412a13aecaedd866094/util/enqueue.go#L45

Its hardcoded now. Instead take it from `env`. This will allow us to dynamically schedule tasks to different runners if more than one exist.

Start at util/enqueue.go around line 45 and inspect how environment values are read before the RabbitMQ queue is selected. Verify the queue name comes from env rather than a hardcoded value, then check the existing project tests or local service setup to confirm tasks can target different runners.

Written by the indexing model from the issue text.