Remove duplicate bound check in function shift

[HaoYang670]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
https://github.com/apache/arrow-rs/blob/master/arrow%2Fsrc%2Fcompute%2Fkernels%2Fwindow.rs#L61-L66

    if offset == 0 {
        Ok(make_array(array.data_ref().clone()))
    } else if offset == i64::MIN || abs(offset) >= value_len {
        Ok(new_null_array(array.data_type(), array.len()))
    } else {
        let slice_offset = clamp(-offset, 0, value_len) as usize;
        ...

When calculate slice_offset, we don't need to compare -offset with value_len, because we have checked abs(offset) >= value_len before.

Describe the solution you'd like
slice_offset should be 0 when offset > 0 (shift left) and -offset when offset < 0 (shift right). Maybe we can use clamp_min

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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