Update Maven CI/CD template to not use "only"
Problem to solve
This CI/CD template uses "only" and should use "rules."
https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Maven.gitlab-ci.yml
This CI/CD template uses "only" and should use "rules."
https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Maven.gitlab-ci.yml