[maven-release-plugin] prepare release xwiki-platform-16.6.0-rc-1

pom.xml

xwiki-platform-core/pom.xml

xwiki-platform-core/xwiki-platform-activeinstalls2/pom.xml

...ctiveinstalls2/xwiki-platform-activeinstalls2-api/pom.xml

...tiveinstalls2/xwiki-platform-activeinstalls2-test/pom.xml

...2-test/xwiki-platform-activeinstalls2-test-docker/pom.xml

xwiki-platform-core/xwiki-platform-administration/pom.xml

...-administration/xwiki-platform-administration-api/pom.xml

...administration/xwiki-platform-administration-test/pom.xml

...on-test/xwiki-platform-administration-test-docker/pom.xml

...st/xwiki-platform-administration-test-pageobjects/pom.xml

...m-administration/xwiki-platform-administration-ui/pom.xml

xwiki-platform-core/xwiki-platform-alerts/pom.xml

...re/xwiki-platform-alerts/xwiki-platform-alerts-ui/pom.xml

xwiki-platform-core/xwiki-platform-annotation/pom.xml

...latform-annotation/xwiki-platform-annotation-core/pom.xml

...-platform-annotation/xwiki-platform-annotation-io/pom.xml

...m-annotation/xwiki-platform-annotation-maintainer/pom.xml

...rm-annotation/xwiki-platform-annotation-reference/pom.xml

...latform-annotation/xwiki-platform-annotation-rest/pom.xml