[GH-2348] Fix STAC tests resilience to external server failures in Scala

[zhangfengcdt]

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-XXX] my subject. Closes #<issue_number>

What changes were proposed in this PR?

This PR makes STAC tests resilient to external server failures by implementing mock-based testing for Python and local test resources for Scala, ensuring tests run reliably without network dependencies.

• Created mock STAC collection JSON files in /spark/common/src/test/resources/stac/:
• 6 collection files (sentinel-2, vegetation, wildfire, copernicus-dem, naip, earthview)
• 1 items file with 10 mock STAC items

How was this patch tested?

• Updated StacDataSourceTest.scala to use local mock files instead of remote URLs
• Updated StacBatchTest.scala to use local resource files with file:// protocol
• Updated StacPartitionReaderTest.scala to use mock items file

Did this PR include necessary documentation updates?

• No, this PR does not affect any public API so no need to change the documentation.

[Copilot]

Pull Request Overview

This PR improves test reliability by replacing external STAC API dependencies with local mock resources, ensuring tests can run without network access and won't fail due to external server issues.

• Replaced remote STAC collection URLs with local mock JSON files
• Created comprehensive mock STAC data including collections and items
• Updated test methods to use file:// protocol for local resources

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
StacPartitionReaderTest.scala	Added helper method for resource paths and replaced HTTPS endpoint with mock items file
StacDataSourceTest.scala	Added helper method and replaced remote collection URLs with local mock files
StacBatchTest.scala	Updated collection URLs and item links to use local mock resources
sentinel-2-items.json	Mock STAC items collection with 10 realistic Sentinel-2 features
wildfire-collection.json	Mock wildfire STAC collection with metadata and links
vegetation-collection.json	Mock vegetation STAC collection with California Forest Observatory data
sentinel-2-pre-c1-l2a.json	Mock Sentinel-2 STAC collection with Earth Search metadata
naip.json	Mock NAIP collection with aerial imagery metadata
earthview-catalog.json	Mock Satellogic EarthView catalog
copernicus-dem.json	Mock Copernicus DEM collection with elevation data

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}