[llvm] [DA] Add tests for nsw doesn't hold on entire iteration space (NFC) (PR #162281)

[Ryotaro Kasuga via llvm-commits]

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kasuga-fj wrote:

Again, monotonicity (and `nsw` of addrecs) don't imply `a * x` doesn't overflow in a signed sense.

https://github.com/llvm/llvm-project/pull/162281