Normalize JIT usages of array length calcuation

[tannergooding]

As per #103778 (comment), there are a few places in the JIT that are using ARRAY_SIZE but the use of ArrLen is preferred where possible.

We should ideally normalize these to be consistent in the JIT and consider whether this is something we want to make more consistent across the codebase as well.

[dotnet-policy-service]

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[tannergooding]

Marked this future as it's low priority consistency cleanup.