`array_repeat` function does not handle null values in count array

[lyne7-sc]

Describe the bug

Follow-up work from PR #20049.

The current implementation of array_repeat does not correctly handle null inputs, which leads to behavior that is
inconsistent with typical SQL null semantics.(potential bug)

To Reproduce

Example input:

array = [1, 2, 3]
count = [2, NULL, 1]

Run:

SELECT array_repeat(array, count);

Current behavior:

[
  [1, 1],
  [], 
  [3]
]

Expected behavior

The function should be null-propagating with respect to count:
If count[i] is NULL, result[i] should be NULL

[
  [1, 1],
  NULL,
  [3]
]

Additional context

No response

[lyne7-sc]

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