Prefer central repo over repository.apache.org

[adoroszlai]

What changes were proposed in this pull request?

CI build is trying to download non-Apache artifacts from repository.apache.org:

[INFO] Downloading from apache-public-repository-group: https://repository.apache.org/content/groups/public/org/codehaus/groovy/groovy-all/2.5.19/groovy-all-2.5.19.pom
[INFO] Downloading from jenkins-releases: https://repo.jenkins-ci.org/releases/org/codehaus/groovy/groovy-all/2.5.19/groovy-all-2.5.19.pom
[INFO] Downloading from repo.jenkins-ci.org: https://repo.jenkins-ci.org/public/org/codehaus/groovy/groovy-all/2.5.19/groovy-all-2.5.19.pom
[INFO] Downloaded from repo.jenkins-ci.org: https://repo.jenkins-ci.org/public/org/codehaus/groovy/groovy-all/2.5.19/groovy-all-2.5.19.pom (25 kB at 309 kB/s)

Repositories defined in pom.xml have higher precedence than central repo inherited from super POM.

See https://infra.apache.org/infra-ban.html ("Excessive 404") for why this is a problem.

This change explicitly adds central as first repository.

(related change: apache/incubator-kie-kogito-runtimes#3816)