Add plus secrets for image building in tests

[ciarams87]

Proposed changes

Problem: The conformance and functional tests are failing to use the cache for the Plus UBI images in main causing the builds to fail

Solution: Add the plus secrets to these steps

Testing: Describe any testing that you did.

Please focus on (optional): If you any specific areas where you would like reviewers to focus their attention or provide
specific feedback, add them here.

Closes #ISSUE

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

NONE

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.83%. Comparing base (20d3910) to head (93733e7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4020   +/-   ##
=======================================
  Coverage   86.83%   86.83%           
=======================================
  Files         128      128           
  Lines       16607    16607           
  Branches       62       62           
=======================================
  Hits        14420    14420           
  Misses       2005     2005           
  Partials      182      182           

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