Add a CleanSpec for the old Android Runtime APEX package.

This package is no longer built, since the introduction of the
"release" and "debug" packages (in CL
https://android-review.googlesource.com/c/platform/art/+/826725).

Test: Run "make nothing" and check that the file has been removed.
Bug: 113373927
Change-Id: Ie29df4d4064d958a55de504f19fd4321b881789f