[Cherry-pick] Fix CVE-2026-34477 (#38210)

[shunping]

Cherry pick #38210 into release 2.73.

[shunping]

r: @jrmccluskey @Amar3tto

[gemini-code-assist]

Summary of Changes

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This pull request performs a cherry-pick of a security fix into the 2.73 release branch. The primary objective is to remediate a vulnerability by upgrading the Log4j2 dependency and ensuring that the patched version is correctly bundled within the expansion service's shaded artifacts.

Highlights

• Security Update: Updated the Log4j2 version to 2.25.4 to address CVE-2026-34477.
• Dependency Enforcement: Forced the inclusion of the updated log4j-core library in the expansion-service shadow jar to mitigate transitive dependency vulnerabilities.

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