Fix CI builds and introduce a maven release lifecycle.

This MR fixes missing ZUUL_ variables, bases builds atop the openjdk8 image and introduces support to maven release lifecycles.

Maven release

A new job has been introduced that triggers maven prepare and maven perform operations. See https://maven.apache.org/maven-release/maven-release-plugin/. The goal at this stage is to introduce a minimum set of config that we can use to publish jar. Might there be interest, we could work towards making a more generic template and refined config.

The goal is to implement the same workflow of other WMF java projects and Python workflow_utils. A release can only be cut from main. Upon release, a new tag is pushed and project version is bumped automatically.

As an example, I performed some releases from a demo branch:

• Release tags https://gitlab.wikimedia.org/repos/data-engineering/mediawiki-stream-enrichment/-/tags
• Artifacts https://gitlab.wikimedia.org/repos/data-engineering/mediawiki-stream-enrichment/-/packages NOTE: these will be removed from Gitlab before this MR is merged.

TODO

[x] remove demo artifacts before merging.~~

cc / @otto @tchin