Update CI Pipeline and Dependencies

What?

CI Pipeline Changes

1. Add maven-build-branch job to handle builds for non-default branches.
2. Update the maven-build / docker-image-build / portainer-trigger jobs to use newer versions of their respective images.
3. In docker-image-build, pull the latest image before building.

Dependencies Updates

1. Update the base image from amazoncorretto:19 to amazoncorretto:21.
2. Minor version bumps for several dependencies in the pom.xml.

Why?

Laying the ground for the YouTube Prosloyka™.