[QCR][Final] Clean up eng/common/templates/post-build folder

[chcosta]

• It's silly that there's no consistency between parameter names in different templates
  ie. "StageLabel" vs "stageName"

• The folder name "post-build" doesn't really make sense because

  • if it really means "post-build", then there's other things that are post-build, like tests

  • it's all in the azure build pipeline now so there's not really a post-build thing happening

  I'd prefer a name like "release"

• It feels like there's this pattern for templates under /eng/common/templates where templates are stored in the folder which represents the type of template reference they are, and then there's this "post-build" folder where there's a completely different convention for folder naming.

We should clean up our templates (parameter usage, filenames, etc...) and follow a defined convention rather than this wild west of template names / locations. The difficulty, at this point, is doing so without making it a breaking change.

[markwilkie]

Is this something that makes sense for the ring v-team to do?

[jcagme]

We can look at it but won't be our top priority

[michellemcdaniel]

This is out of scope for #6418.