Implement DAG for release pipeline

Balasankar 'Balu' Crequested to merge
implement-dag-in-release-pipeline into master

What does this MR do?

  1. Implement DAG for release pipeline so that releases can technically start as soon as relevant packages are ready
  2. Consolidate stages that are now obsolete. This means gitlab_com:* jobs are going away in favor of ability to run jobs out of order.
  3. package-and-image stage is being split to package and image. Ubuntu jobs will go to package stage with other OSs, and Docker jobs will go to image stage. This will need changes in release-tools to update stages jobs in which are played during publish.
Edited by Balasankar 'Balu' C

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