[llvm] [ARM] Delete llvm/test/MC/ARM/directive-type-diagnostics.s (NFC) (PR #201080)

[Cullen Rhodes via llvm-commits]

c-rhodes wrote:

> I am not sure if there is a reason to having two folders, but I would be tempted to remove the version in MC/ELF/ARM, mostly as the folder already contains less files.

there's an equivalent test for MachO so I figured best to keep the one under ELF: https://github.com/llvm/llvm-project/blob/main/llvm/test/MC/MachO/ARM/directive-type-diagnostics.s

happy to move if preferred tho

https://github.com/llvm/llvm-project/pull/201080