fix(tests): isolate feature user defaults

[Kyle-Ye]

Summary

• Use a dedicated UserDefaults suite and the Feature1 key to isolate the feature test from other tests that read standard defaults.
• Reset the test value and cache before and after execution while preserving the existing cache and override assertions.

[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Ran test modules	Commit
OpenSwiftUI	✅	7	552459fe3

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	41.6s	552459fe3

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.26%. Comparing base (a75b531) to head (4f286dc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1103      +/-   ##
==========================================
+ Coverage   28.88%   33.26%   +4.37%     
==========================================
  Files         752      805      +53     
  Lines       55545    63992    +8447     
==========================================
+ Hits        16043    21285    +5242     
- Misses      39502    42707    +3205     

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