[CVP] Use simpler urem expansion when LHS >= RHS (PR63330)

In this case we don't need to emit the comparison and select.

This is papering over a weakness in CVP in that newly added
instructions don't get revisited. If they were revisited, the
icmp would be folded at that point.

However, even without that it makes sense to handle this explicitly,
because it avoids the need to insert freeze, which may prevent
further analysis of the operation by LVI.

Proofs: https://alive2.llvm.org/ce/z/quyBxp

Fixes https://github.com/llvm/llvm-project/issues/63330.