Update What's new in Maven 4 before release

### Improvement proposal

Release gets closer (see [Mailing list](https://lists.apache.org/thread/jnb3snhdm4b564gz8hbctp9rfk8fc67n)) so we want to double check the ["What's new in Maven 4?"](https://maven.apache.org/whatsnewinmaven4.html) article if everything is covered.

Points:
* add / highlight the [Maven Upgrade Tool](https://maven.apache.org/tools/mvnup.html)
* wrt CI-friendly versions, it's worth nothing that the name of the properties aren't limited anymore, however, they have to be defined at build time
* for automatic versioning, it could be worth mentioning that the parent itself can be inferred by simply using ``, in which case, the pom from the parent directory will be used
* in consumer POM, we removed the non transitive dependencies, so mainly the test dependencies (given they're not transitive, their presence in the consumer pom is useless)
* Upgrade tool: update deprecated phases (see https://github.com/apache/maven/pull/11215 )

edit: the points above a contained in #1429 and #1430