Bootstrap content / hst configuration by essential plugins should not have jcr uuid property in general

there is no point in different projects all using the, say, same jcr:uuid for the sitemap item created by the sitemap plugin. In the best case, having jcr:uuids doesn't harm. So, let's remove them where possible. When used in example content with for example a hippo:docbase in a mirror pointing to some uuid, the uuid cannot be removed