Synchronized parallel suite batches

This release fixes a reliability issue in parallel test suites where interdependent pipelines could start out of sync.

🐞 Bug fixes

Synchronized parallel suite batches

Parallel suites now start each reserved batch of tests together, making publisher/subscriber and other interdependent pipeline suites more reliable.

Use the existing suite.mode: parallel configuration:

suite:
  name: pipeline-suite
  mode: parallel
  min_jobs: 2

When enough jobs are available for the whole suite, all suite members start together. When the suite is larger than --jobs, the harness runs synchronized batches instead.

By @IyeOnline and @codex.