AFAIK, ErraiUI properly inherits all its own dependencies so removing any of these things shouldn't break ErraiUI itself. As for declaring the things uberfire-client-webapp uses directly, I think this set should be sufficient:

    <inherits name="org.jboss.errai.ui.UI" />
    <inherits name="org.jboss.errai.bus.ErraiBus" />
    <inherits name="org.jboss.errai.enterprise.CDI" />