Upgrade GitHub Actions to Node.js 24-compatible releases

[arnabnandy7]

Problem

The CI workflows currently use actions/checkout@v4 and actions/setup-java@v4. These releases use deprecated Node.js 20 or Node.js 16 action runtimes.

Proposed change

Upgrade to actions/checkout@v7 and actions/setup-java@v6, preserving existing workflow conditions, inputs, secrets, and behavior.

Acceptance criteria

• All affected actions use published Node.js 24-compatible releases.
• Workflow syntax and YAML validation pass.
• No affected deprecated action references remain under .github/workflows.
• Existing build, test, notification, and deployment behavior remains unchanged.

Related organization-wide tracking: embabel/embabel-agent#1999