Make the AMD ABL regtest stable on GPUs

[moprak-nrel]

Summary

Perturb temperature/velocity values so that the regtest values aren't too small for SGS terms. Currently the alpha_eff is close to machine precision leading to flaky regtest runs on GPUs.

Pull request type

Please check the type of change introduced:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe): update regtest parameters

Checklist

The following is included:

• new unit-test(s)
• new regression test(s)
• documentation for new capability

This PR was tested by running:

• the unit tests
  • on GPU
  • on CPU
• the regression tests
  • on GPU
  • on CPU

Additional background

Issue Number: