TRIB-223: removes all remaining usages of AbstractTestConstants and deletes class

[mrsbluerose]

Removed usages of AbstractTestConstants from:

• UserPrincipalTest
• ToBeReviewedCheckerServiceImpl_checkPartOfSpeechTest
• ToBeReviewedCheckerServiceTest
• UserDetails test (removed unused import)

Deleted AbstractTestConstants class

Testing:

• mvn clean test runs successfully
• mvn clean verify runs successfully

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.55%. Comparing base (09d2630) to head (def39ab). Report is 2 commits behind head on develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #286 +/- ## ========================================== Coverage 82.55% 82.55% Complexity 556 556 ========================================== Files 79 79 Lines 1685 1685 Branches 275 275 ========================================== Hits 1391 1391 Misses 254 254 Partials 40 40 ```

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