[llvm] [DA] Rewrite BanerjeeMIV test with safe APInt interval arithmetic (PR #207662)

[Ryotaro Kasuga via llvm-commits]

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kasuga-fj wrote:

```suggestion
/// Walks through the subscript and collects the coefficient and maximum
/// iteration index associated with each loop level. Both are extended to the
/// widened analysis type before Banerjee arithmetic.
```

This is a pre-existing issue, but please use `///` for function header comments. The same applies elsewhere.

https://github.com/llvm/llvm-project/pull/207662