[CIR][NFS] Remove unnecessary constraints asserts in VecCmpOp (#142473)
We already have constraints in CIROps to make sure that the operands and
result type are vectors
[VecCmpOp](https://github.com/llvm/llvm-project/blob/b88dfb0b23d0a1863414fb9450ee444766bfe7c9/clang/include/clang/CIR/Dialect/IR/CIROps.td#L2149-L2151)