[llvm] [NFC] Reduce fragility of swdev503538-move-to-valu… test (PR #170702)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

I'd rather keep the IR test. The move to valu detail is an implementation defect which should be fixed in the future (actually I thought we handled this correctly now)? MIR tests are much less maintainable and generally should be avoided. 

https://github.com/llvm/llvm-project/pull/170702