[VPlan] Fix miscompile after PR #142433. (#147398) This fixes a bug introduced by aa2402931908317f5cc19b164ef17c5a74f2ae67, "[VPlan] Unroll VPReplicateRecipe by VF", which cloned a VPReplicateRecipe without transferring the flags from the original. That can cause incorrect nsw/nuw flags to be emitted on the new instructions, which may result in miscompiles. It turns out there were no test-cases in the repo which end up hitting the situation where the recipe requires instruction clones to have different flags from the underlying instruction. The existing tests covered the flags being correct when the replacement instruction is a vectorized version of the initial instruction, but not when it required clones. A new test is added covering this.
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