[80]: Replace --pipelined=True with --batch-wait-ms=X

[SomeoneSerge]

Instead of choosing between the whole eval to finish or disabling scheduling altogether (i.e. scheduling jobs one by one as they come), do something like like "wait X milliseconds to accumulate a batch of jobs, run the solver on this subset, schedule some builds, then wait another X milliseconds to extend the batch and re-run the solver to get a better plan"

It is OK to focus on the "complete eval first" scenario and implement batching later: our scope is to find a good way to choose a build plan, not in speeding up the eval