Fix Java release workflow deploy credentials setup

[Copilot]

The Java release workflow was failing in the build job during mvn deploy because the Sonatype Central publishing plugin could not resolve the central server configuration from Maven settings. This updates the workflow so Maven publishing settings are regenerated immediately before the release deploy step.

• Root cause

  • The release workflow reached mvn clean deploy without a valid settings.xml entry for server id central.
  • As a result, the Central publishing plugin failed before upload.

• Workflow change

  • Add a dedicated actions/setup-java@v4 step right before deploy.
  • Reconfigure:
    • server-id: central
    • server-username: MAVEN_USERNAME
    • server-password: MAVEN_PASSWORD
    • gpg-private-key
    • gpg-passphrase: GPG_PASSPHRASE

• Effect

  • Ensures the deploy step runs with fresh Maven Central credentials and GPG settings in the runner’s Maven configuration.
  • Keeps the build/generation steps unchanged.

• Relevant workflow snippet

  - name: Configure Maven Central publishing
    uses: actions/setup-java@v4
    with:
      distribution: 'temurin'
      java-version: '21'
      server-id: central
      server-username: MAVEN_USERNAME
      server-password: MAVEN_PASSWORD
      gpg-private-key: ${{ secrets.GPG_PRIVATE_KEY }}
      gpg-passphrase: GPG_PASSPHRASE