[GH-2392] Test single-member GeometryCollection

[ryux1]

Did you read the Contributor Guide?

The contributor rules and Python development/test instructions were reviewed while preparing this patch.

Is this PR related to a ticket?

Yes. Partially addresses #2392.

What changes were proposed in this PR?

Extend the shared GeoSeries parity fixtures with a missing single-member GeometryCollection containing a closed LineString. Because self.geomcollection is part of self.geoms, the case flows through the existing Sedona-versus-GeoPandas checks, including construction, serialization, predicates, measurements, transformations, and is_closed.

The initial revision also included a collection whose members were all typed empty geometries. The full matrix demonstrated a distinct to_arrow WKB dimensionality mismatch for that shape, now tracked separately in #3329; it was removed here rather than masking a real defect with an expected failure.

How was this patch tested?

• Black 26.5.1 formatting check
• Python bytecode compilation
• git diff --check
• Reference GeoPandas 1.1+ / Shapely 2.1+ evaluation of the fixture, including is_empty, is_valid, is_closed, has_z, geom_type, length, area, and count_geometries
• Upstream CI on the initial revision: 2,092 tests passed and the only failure was the separately tracked all-empty-member serialization mismatch in GeoSeries.to_arrow differs for all-empty GeometryCollection members #3329
• Focused distributed checks for the narrowed fixture: constructor plus all four explode variants passed (5 tests)
• Broader fail-fast run: 44 passed and 1 skipped before test_coverage_validation reached an internal JVM function absent from the released Sedona 1.9.0 shaded JAR used locally

Did this PR include necessary documentation updates?

No. This only expands test coverage and does not change a public API.

[jiayuasu]

Thank you!