[CIR] Use per-element zero-initialization with array new (#187760)
There was a discrepancy between the CIR and classic codegen handling of
zero-initialization of constructed objects with array new. Classic
codegen performs zero-initialization on a per-element basis, while CIR
had been inserting a single zero-initialization of the entire array
before individually constructing the elements.
This change aligns the CIR behavior with the classic codegen behavior.