[llvm] [libc] add uefi fullbuild to workflows (PR #131376)

[Tristan Ross via llvm-commits]

RossComputerGuy wrote:

I had to disable SCUDO because things weren't targeting right there. This hasn't been a problem locally, might be my own problem with configuring it or just due to setting the default target triple when building Clang. Anyway, for now we can live without SCUDO on UEFI and likely work with supporting the built-in allocator for UEFI in the future.

https://github.com/llvm/llvm-project/pull/131376