aidl_unittests: remove dup'd C++ 'goldens' am: 19a05d40be am: 8c2c02cb76

Original change: https://android-review.googlesource.com/c/platform/system/tools/aidl/+/1666499

Change-Id: Id9c39e7092fc058bbb577b0b19aa571483a3ea8d