[GH-2450] chore(geopandas): write sjoin match tests for dwithin()

[bunnysocks]

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide

Is this PR related to a ticket?

• Yes, and the PR name follows the format [GH-2450] chore(geopandas): write sjoin match tests for dwithin().
  Closes chore(geopandas): Write sjoin match tests for dwithin() #2450

What changes were proposed in this PR?

This PR adds new tests to improve coverage for Sedona’s GeoPandas integration, specifically for the sjoin() function using the predicate="dwithin" parameter.

Key updates:

• Added a new test module test_sjoin_match.py under sedona/python/tests/geopandas/.
• Implemented comparisons between Sedona’s and GeoPandas’ sjoin() outputs for dwithin() predicate.
• Covered edge cases including:
  • Varying distance thresholds (0.5, 0.05, etc.)
  • Empty and small-distance joins
  • Type and integrity checks on returned GeoDataFrames

These tests aim to ensure Sedona’s spatial join behavior matches GeoPandas’ expected results and help detect future regressions.

How was this patch tested?

• Manually verified using pytest locally.
• Confirmed that:
  • Both Sedona and GeoPandas return equivalent results for valid dwithin() joins.
  • Output GeoDataFrames contain consistent left/right ID pairs.
• CI will re-verify via automated testing upon PR submission.

Did this PR include necessary documentation updates?

• No, this PR does not affect any public API, so no documentation changes are required.

[Copilot]

Pull request overview

Adds GeoPandas parity tests for Sedona’s sjoin() with predicate="dwithin" to strengthen regression coverage for distance-based joins in the GeoPandas integration test suite.

Changes:

• Introduces a new test_sjoin_match.py module that compares Sedona vs GeoPandas sjoin(dwithin) results.
• Adds parameterized coverage across multiple distance thresholds and a left-join unmatched-row preservation check.
• Normalizes join outputs to compare row-pairs deterministically across implementations.

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