[clang-tools-extra] [llvm] [llvm] Remove the Legacy PM Hello example (PR #95708)

[Andrzej Warzyński via cfe-commits]

banach-space wrote:

> You also need to remove the use of this pass (for testing purposes) from clang-tools-extra.

Done, thanks!

I don't understand why CI still fails:
```bash
Total Discovered Tests: 60135
--
  | Skipped          :    15 (0.02%)
  | Unsupported      :  1005 (1.67%)
  | Passed           : 58946 (98.02%)
  | Expectedly Failed:   169 (0.28%)
  | ninja: build stopped: cannot make progress due to previous errors.
  | + show-stats
  | + mkdir -p artifacts
  | + ccache --print-stats
  | 🚨 Error: The command exited with status 1
```

Can you see the actual failure? Looks like all tests passed, right?

https://github.com/llvm/llvm-project/pull/95708