This attribute was introduced in
7eca38ce76d5d1915f4ab7e665964062c0b37697 (llvm-project).
Match it using a wildcard regex, since it is not relevant to these
tests.
This is intended to reduce future conflicts with rebranch.
Also, make some related changes, like updating a path in the Android doc, making sure the
`unknown` vendor is always used, and using `CPU` instead of `CODEGENERATOR`.