Model Builder: fix config access, add UT, clean up CI yamls

[jambayk]

Describe your changes

• Fix config access in model builder pass
• Add unit test for model builder. CPU tests now has its own requirements file.
• Do some clean up in the pipeline yamls:
  • set gpu defaults in gpu test templates
  • removed unused device template parameters
  • remove redundant parameter assignment from template calls
  • nightly gpu test uses gpu image

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.
• Is this PR including examples changes? If yes, please remember to update example documentation in a follow-up PR.

(Optional) Issue link

Fixes #1635