Update IsStrictRun to be framework-only

This change guards IsStrictRun using __ANDROID_VNDK__ to avoid needing
to update the prebuilt ABI dumps in internal, since IsStrictRun is only
needed in the framework and does not need to be made available to
vendors.

This avoids updating the API surface unnecessarily.

Test: Cherry-pick this change to internal and verify that internal
      builds work without needing to update the prebuilt ABI dumps.
Bug: 283326935
Change-Id: I9dfdf3306b6a9b0faa9f8f7871b1fc244bde1a97