test: Enable Default Union Graph in TriplestoreServiceInMemory (DEV-3295)

[BalduinLandolt]

Pull Request Checklist

Task Description/Number

Issue Number: DEV-

PR Type

• build/chore: maintenance tasks (no production code change)
• docs: documentation changes (no production code change)
• feat: represents new features
• fix: represents bug fixes
• perf: performance improvements
• refactor: represents production code refactoring
• test: adding or refactoring tests (no production code change)

Basic requirements for bug fixes and features

• Tests for the changes have been added
• Docs have been added / updated

Does this PR introduce a breaking change?

• Yes

Does this PR change client-test-data?

• Yes

[linear]

DEV-3295 Enable default union graph in all cases for in-memory triplestore service

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (eac5751) 11.74% compared to head (7a01da4) 12.01%.
Report is 74 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3052      +/-   ##
==========================================
+ Coverage   11.74%   12.01%   +0.27%     
==========================================
  Files         246      262      +16     
  Lines       22907    22699     -208     
==========================================
+ Hits         2690     2728      +38     
+ Misses      20217    19971     -246     

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