Investigate splitting up the publish_draft_releases workflow

[Garandor]

publish_draft_releases.yml currently contains

• integration tests
• docker test on normal PRs

and the draft release generation on release candidates.

I open the file, see 1152 lines and immediately feel regret for doing so.

To reduce complexity and in the spirit of single-responsibility we should refactor this into multiple files, so that publish_draft_releases does exactly what the name implies and nothing more

look into https://docs.github.com/en/actions/using-workflows/reusing-workflows for modularzation

[ghzlatarev]

More ideas: https://github.com/Manta-Network/Manta/pull/681#pullrequestreview-1040662163

[ghzlatarev]

https://github.com/Manta-Network/Manta/pull/781#discussion_r961006897