fix auth tests for RHOAI

[StevenTobin]

Description

e2e failures in #1674 seem to be caused by the function for returning the adminGroup getting an empty platform and returning the wrong group. Fix this by setting the group in the test.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 22.18%. Comparing base (2c5e52a) to head (6e57ef1).
Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1700      +/-   ##
==========================================
+ Coverage   22.15%   22.18%   +0.03%     
==========================================
  Files         165      168       +3     
  Lines       11302    11384      +82     
==========================================
+ Hits         2504     2526      +22     
- Misses       8542     8600      +58     
- Partials      256      258       +2     

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[zdtsw]

i am not sure i understand this change:
so this is to test if the platform is for self-managed or managed, and error out?
but the test should not care about this,
instead (simiar to validateRemovingGroups):

• if platform is cluter.OpenDataHub || cluster.Unknown=> odh-admins as AdminGroups[0]
• if is SelfManaged => rhods-admins as AdminGroups[0]
• if is Managed => dedicated-admins