[llvm] [SandboxIR][Region] Auxiliary vector metadata now requires a region (PR #137443)

[Jorge Gorbe Moya via llvm-commits]

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

If you have a plan to untangle Region and cost tracking I don't think it's worth blocking on this now. Approving with a small nit.

https://github.com/llvm/llvm-project/pull/137443