Fix Explorer when a component contains multiple contributions to the same extension point

<extension point="configuration" target="org.nuxeo.runtime.ConfigurationService">
    <documentation>
      Controls whether iterations in document listings are done
      using build-time tag c:forEach or render-time tag ui:repeat (which is much
      more efficient on large content).

      Using render-time iterations may break
      some behaviours, this property is mainly useful for backport of
      optimizations on maintenance branches.

      @since 8.2
    </documentation>
    <property name="nuxeo.jsf.listings.useRepeatRenderTime">true</property>
  </extension>