Fix watchOS CI builds/tests

[joshedney]

Goal

Fix the flakey watchOS 7/8 tests on CI

Changeset

Change the default SDK for watchOS tests to watchsimulator

Dynamically get the name of the watchOS device due to an issue with naming after running xcodebuild -downloadAllPlatforms

Testing

Covered by CI

[github-actions]

Bugsnag.framework binary size decreased by 200 bytes from 713,304 to 713,104 🎉

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  [ = ]       0  +2.6%    +200    [__LINKEDIT]
  +0.2%     +32  +0.2%     +32    __DATA,__cfstring
  +0.2%     +30  +0.2%     +30    __TEXT,__cstring
  +0.0%      +2  +0.0%      +2    [__TEXT]
  -0.5%      -8  -0.5%      -8    Indirect Symbol Table
  -0.6%      -8  -0.6%      -8    __DATA,__la_symbol_ptr
  -0.0%      -8  -0.0%      -8    __TEXT,__text
  -0.6%     -12  -0.6%     -12    __TEXT,__stub_helper
  -0.6%     -12  -0.6%     -12    __TEXT,__stubs
  -0.6%     -24  -0.6%     -24    Lazy Binding Info
  -0.3%     -24  -0.2%     -24    [__DATA]
  -0.0%     -72  -0.0%     -72    String Table
  -0.1%     -96  -0.1%     -96    Symbol Table
  -0.0%    -200  [ = ]       0    TOTAL

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