Check process-usertasks-custom-lifecycle-quarkus example after recent HT changes

Following up on the changes from https://github.com/apache/incubator-kie-issues/issues/1484, the process-usertasks-custom-lifecycle-quarkus example should be checked and eventually updated:
* Possible changes required to the example's README file
* Verify if custom lifecycle still works as expected/documented

Start with issue 1484 and the README for the process-usertasks-custom-lifecycle-quarkus example to understand the recent HT changes. Verify whether the custom lifecycle still works as documented, then update the example README if its instructions or behavior have changed.

Written by the indexing model from the issue text.