Adds integration test for updating subdomain alone

[cmgrote]

Note

Adds an integration test to validate upserting a subdomain without altering domain hierarchy, plus a minor dependency bump.

• New UpdateSubdomainTest creates a domain/subdomain, runs Importer with subdomain-alone.csv (upsert), and asserts the hierarchy remains unchanged; also verifies output files and error-free logs
• Adds subdomain-alone.csv test fixture
• Bumps awssdk version to 2.40.17 in gradle/libs.versions.toml

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