convert column table to arrow if arrow present

[shivam2680]

What type of PR is this?

• Refactor
• Feature
• Bug Fix
• Other

Description

How is this tested?

• Unit tests
• E2E Tests
• Manually
• N/A

Related Tickets & Documents

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[Copilot]

Pull Request Overview

This PR updates the behavior of fetching query results by converting a ColumnTable to a PyArrow Table when PyArrow is available. It adds a new end-to-end test to validate that the catalogs() API returns a PyArrow Table and updates the fetchall_arrow() method in the client to merge columnar results when appropriate.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tests/e2e/test_driver.py	Added test_catalogs_returns_arrow_table to verify arrow table conversion.
src/databricks/sql/client.py	Updated fetchall_arrow() to merge ColumnTables and convert the final result where PyArrow is present.