Make service name configurable during job submission

[Sovietaced]

We have a use case where we are submitting a gang of jobs for scheduling and it would be beneficial to have a deterministic and stable service name during submission time. More specifically we are submitting a Ray cluster with a head node and many worker nodes. The worker nodes use an init-container to block until the head node is reachable via a service. Given that we are using third-party containers it would be nice if we could define the jobs and init containers such that they referenced a predefined service name instead of implementing service discovery at runtime to learn of the service name based on the non-deterministic job ID.