[llvm] [UTC][VPlan] Use `-vplan-print-after` for VPlan-dump-based tests (PR #178736)

[Florian Hahn via llvm-commits]

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

LGTM, thanks!

Please let me know if you'd like me to merge this once the merge conflicts are fixed

https://github.com/llvm/llvm-project/pull/178736