Remediate Jackson-databind CVEs and instrumentation-verifier failure

[IshikaDawda]

Description

1. Jackson-databind CVE remediation (CVE-2026-54512/54513, severity 9.2/9.3)
   newrelic-security-agent bumped jackson-databind and jackson-dataformat-properties 2.14.2 → 2.18.9.
   THIRD_PARTY_NOTICES.md updated both jackson entries to include latest version details.

2. Broken build infrastructure (JCenter shutdown)
   removed jcenter() repository declarations. JCenter shut down in 2021; the JVM's TLS handshake to it fails outright now, which was blocking dependency resolution for buildSrc (needed to fetch the shadow plugin) and other modules. Added gradlePluginPortal()/plugins.gradle.org maven repo where mavenCentral() alone didn't carry the plugin coordinates (shadow 6.0.0 was only ever published to JCenter/Plugin Portal).

3. Shadow jar build failure caused by the jackson bump
   Bumping jackson-databind was causing build failure due to Unsupported class file major version 61 to resolve this added excludes for META-INF/versions/17/** and META-INF/versions/21/** in the relocatedShadowJar task.

4. Instrumentation verification failure fixes:
   jsp-3 and servlet-6.0 added excludeRegex to exclude milestone/beta versions
   Fixed the verification error observed in lettuce-5.0 due to deprecation of a member's function and used toString() instead of name().

5. Dynamodb unit tests were using jackson-databind 2.6.x which has PropertyNamingStrategy.PascalCaseStrategy. The project-wide test jackson-databind bump (for CVE remediation) would otherwise win dependency resolution and break it. So, forced used 2.6 version for dynamodb unit tests.