test: Use XCTestExpectation for User

[philipphofmann]

Replace the dispatch group with an XCTestExpectation to get a failure message when the wait times out.

Contributes to GH-5789

#skip-changelog

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.644%. Comparing base (d23a1b1) to head (a6c470b).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #5848       +/-   ##
=============================================
+ Coverage   86.554%   86.644%   +0.089%     
=============================================
  Files          422       423        +1     
  Lines        36273     36405      +132     
  Branches     17136     17223       +87     
=============================================
+ Hits         31396     31543      +147     
+ Misses        4833      4815       -18     
- Partials        44        47        +3     

see 20 files with indirect coverage changes

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[philprime]

LGTM