Reenabled Havok LLPhysicsExtensions for Rosetta

[brad-linden]

Reenable havok llphysicsextensions on Darwin x86_64 with llphysicsextensions_stub used for aarch64

Description

Related Issues

• Please link to a relevant GitHub issue for additional context.
  Issue Link: partial fix for Disable model upload on Apple Silicon builds with user guidance #4757 when running under rosetta

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Additional Notes