chore: update comment about needs_interchanging

[MarcoGorelli]

This comment wasn't totally accurate, sorry

The flag indicates whether the object needs converting to PyArrow, but this doesn't necessarily happen via the interchange protocol. For DuckDB and Ibis, we just call their native "to arrow" methods, the interchange protocol is just the last fallback

In any case, I think that how exactly the conversion happens is an implementation detail, what Plotly sees is just that a conversion to PyArrow happens:

args["data_frame"] = nw.from_native(
    args["data_frame"].to_arrow(), eager_only=True
)

[LiamConnors]

Thanks @MarcoGorelli !