[SPARK-52407][SQL][FOLLOWUP] Expression description fix for ThetaIntersectionAgg

[cboumalh]

What changes were proposed in this pull request?

This PR corrects the @ExpressionDescription usage text for theta_intersection_agg function. The usage description was updated from:

_FUNC_(expr, lgNomEntries)

to:

_FUNC_(expr)

Why are the changes needed?

The previous documentation incorrectly showed lgNomEntries as a parameter for theta_intersection_agg. This function only accepts a single expression parameter, unlike theta_sketch_agg and theta_union_agg which both accept an optional lgNomEntries parameter. This change ensures the documentation accurately reflects the function's signature and provides a clearer description of what the function does.

Does this PR introduce any user-facing change?

Yes - the documentation shown in SQL help/describe function output for theta_intersection_agg will now correctly show only one parameter instead of two, and will include a more descriptive explanation of the function's behavior.

How was this patch tested?

The change is documentation-only. The function signature and implementation remain unchanged. Existing tests for theta_intersection_agg continue to validate the correct behavior.

Was this patch authored or co-authored using generative AI tooling?

No

[cboumalh]

cc @dongjoon-hyun @cloud-fan @dtenedor Hi all, I noticed this minor documentation error. If any of you have the time to take a look, that would be great. Thank you!!