[polly] [Polly] Add vectorize metadata to loops identified as vectorizable by polly (PR #113994)

[Michael Kruse via llvm-commits]

https://github.com/Meinersbur approved this pull request.

I'd prefer `-polly-annotate-metadata-vectorize` always-on which requires regression test changes. If you can do that it would be great, but the patch is already fine as-is, so LGTM.

https://github.com/llvm/llvm-project/pull/113994