[llvm] [IVDesc] Make getCastInsts return an ArrayRef (NFC) (PR #169021)

[Florian Hahn via llvm-commits]

================
@@ -454,9 +454,7 @@ class InductionDescriptor {
   /// Returns a reference to the type cast instructions in the induction
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fhahn wrote:

```suggestion
  /// Returns an ArrayRef to the type cast instructions in the induction
```


https://github.com/llvm/llvm-project/pull/169021