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.
Ignore-AOSP-First: This is already in AOSP, but needs to be
                   cherry-picked here first before being removed from
		   AOSP.
Bug: 283326935
Change-Id: I9dfdf3306b6a9b0faa9f8f7871b1fc244bde1a97