[llvm] [msan][NFCI] Add test for llvm.x86.vcvtph2ps.{128, 256} (PR #131244)

[Thurston Dang via llvm-commits]

thurstond wrote:

CI failures are unrelated (https://buildkite.com/llvm-project/github-pull-requests/builds/157165#0195921f-63b3-4da9-a4e1-7538cf3beb26):
* BOLT.X86/icf-safe-icp.test
* BOLT.X86/icf-safe-process-rela-data.test
* BOLT.X86/icf-safe-test1.test
* BOLT.X86/icf-safe-test2GlobalConstPtrNoPic.test

https://github.com/llvm/llvm-project/pull/131244