move `ArrayBuilder::new` to a test-only trait

[xiangjinwu]

risingwave/src/common/src/array/list_array.rs

Lines 51 to 64 in 89b778e

	#[cfg(not(test))]
	fn new(_capacity: usize) -> Self {
	panic!("please use `ListArrayBuilder::with_type` instead");
	}
	#[cfg(test)]
	fn new(capacity: usize) -> Self {
	// TODO: deprecate this
	Self::with_type(
	capacity,
	// Default datatype
	DataType::List(Box::new(DataType::Int16)),
	)
	}