[clang] [analyzer] Fix a crash from element region construction during `ArrayInitLoopExpr` analysis (PR #113570)

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isuckatcs wrote:

> I presume that you understand its role

I don't remember why I did it with pattern matching. I guess, I wasn't aware that `getSVal()` will return the binding even if it's enveloped by other expressions.

https://github.com/llvm/llvm-project/pull/113570