Refactored GitHub Actions workflows for better structure, secret management and image handling

[danielFlemstrom]

• Updated build, test, and publish workflows to use secrets instead of inputs.
• Ensured the image tag is properly handled based on build success or failure.
• Improved logging by printing the image tag in build, test, and publish steps.
• Adjusted the Docker login step to correctly reference secrets.
• Simplified concurrency in test jobs and removed unnecessary buildx setup from the build workflow.