Update ContainerRef.shouldDetermineEffectiveRegistry test to not be machine dependent

[jonesbusy]

Description

Update ContainerRef.shouldDetermineEffectiveRegistry test to not be machine dependent

Testing done

Run test on a machine with custom registries.conf.

Adapt the test so it doesn't fail

Submitter checklist

• I have read and understood the CONTRIBUTING guide
• I have run mvn license:update-file-header, mvn spotless:apply, pre-commit run -a, mvn clean install before opening the PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.05%. Comparing base (f089fdb) to head (3581847).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #596      +/-   ##
============================================
+ Coverage     88.51%   89.05%   +0.53%     
  Complexity      821      821              
============================================
  Files            42       42              
  Lines          2439     2439              
  Branches        299      299              
============================================
+ Hits           2159     2172      +13     
+ Misses          168      155      -13     
  Partials        112      112              

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