feat(workflows): Add reusable workflow files

[candiduslynx]

Add reusable workflows that will allow us to reuse the common job definitions:

• source plugin tests
  • adds ability to implement bug(aws,gcp,k8s,azure): Test caching in CI does not work #9388 in a single place
• plugin release validation
• runner resolving

Once this part is in the main we can switch parts of the workflows to the reusable ones.

Example implementation: #9541 (aws source).

[candiduslynx]

@erezrokah I think we might want to reconsider what runners we want to be used & when.
I propose using the large runners on main branch only or not use them at all.

The reason for them is simple: we would move from caching during release to caching from main branch. This enables:

1. Direct hits from other branches, as caches are inherited from the default branch (main)
2. Always storing the cache only from main

[erezrokah]

@erezrokah I think we might want to reconsider what runners we want to be used & when. I propose using the large runners on main branch only or not use them at all.

The reason for them is simple: we would move from caching during release to caching from main branch. This enables:

1. Direct hits from other branches, as caches are inherited from the default branch (main)
2. Always storing the cache only from main

Can you open an issue describing the reasoning? I don't think a PR is the right place to discuss why we should do something nor do I see a downside with using large runners for PRs for big plugins.
Additionally we should discuss any caching changes in an issue as I'm not sure we'd like to mix between caches without properly discussing the impact

[candiduslynx]

Drop for now, take another shot after #9780