[llvm] [X86] Modify tests for constrained rounding functions (PR #116951)

[Serge Pavlov via llvm-commits]

spavloff wrote:

Of all changef functions only some cannot be evaluated at compile time:

```
@constrained_vector_rint_v2f64()
@constrained_vector_rint_v3f64()
@constrained_vector_rint_v4f64()
@constrained_vector_nearbyint_v2f64()
@constrained_vector_nearby_v3f64()
@constrained_vector_nearbyint_v4f64()
```

They are put back to the test file.

https://github.com/llvm/llvm-project/pull/116951