[clang] [clang][test] Split AArch64 target feature checks across multiple lines. NFC (PR #99365)

[Jon Roelofs via cfe-commits]

jroelofs wrote:

This broke the aix-ppc64 bot:

https://lab.llvm.org/buildbot/#/builders/64/builds/335

Must have a different version of `sed` than I do :(

https://github.com/llvm/llvm-project/pull/99365