[llvm] [LV][NFC] Add "REQUIRES: assert" to new test file (PR #180522)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

It may help to make it easier if we had a sub-directory for VPlan tests: https://github.com/llvm/llvm-project/pull/180611

Then there's no need to add `REQUIRES:`

https://github.com/llvm/llvm-project/pull/180522