REFACTOR: Migrate Account service tests to Swift Testing

[codecov[bot]]

Codecov Report

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

Project coverage is 89.43%. Comparing base (9fa909b) to head (35aaf94). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #191 +/- ## ======================================= Coverage 89.43% 89.43% ======================================= Files 203 203 Lines 2820 2820 ======================================= Hits 2522 2522 Misses 298 298 ```

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