test: fix frame sizing and view graph test isolation

[Kyle-Ye]

Summary

• Disable hosting safe area regions in the flex frame sizing test on iOS and visionOS so window insets do not change its expected size.
• Run ViewGraphTests on the main actor to serialize access to shared view graph update state.

[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Cache hit rate	Tests	Skipped	Ran	Commit
OpenSwiftUI	✅	0 %	1241	0	1241	e0249eedc

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	39.6s	e0249eedc

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.11%. Comparing base (5af2b2b) to head (e14ca67).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1090      +/-   ##
==========================================
+ Coverage   28.87%   33.11%   +4.24%     
==========================================
  Files         750      803      +53     
  Lines       55271    63659    +8388     
==========================================
+ Hits        15958    21081    +5123     
- Misses      39313    42578    +3265     

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