This is a followup to #53763.

Currently when you start a job that has allow_lazy_open/allow_lazy_start set to true a success response does not make crystal clear whether the job has started work immediately or has started lazily and is waiting for capacity to become available.

We could make this much clearer by adding another field to the response of the open job, start datafeed and start data frame analytics job endpoints.

For example, we could have:

{
  "opened": true,
  "awaiting_lazy_assignment": true
}

{
  "started": true,
  "awaiting_lazy_assignment": true
}

{
  "acknowledged": true,
  "awaiting_lazy_assignment": true
}

Or we could use a different field name instead of awaiting_lazy_assignment.