Fix empty-label of nuxeo-favorites list not appearing with POST Page Provider method

After extending configuration to have Page Providers use POST method, the empty-label message "You haven't starred documents yet" seen in nuxeo-favorites when no results are returned does not render as expected.

Steps to Reproduce:

1. In LTS 2021 instance, configure Page Providers to use POST method using the following contribution:

   <extension target="org.nuxeo.runtime.ConfigurationService" point="configuration">
     <property name="org.nuxeo.web.ui.pageprovider.method">POST</property>
   </extension>

2. In Web UI without any Favorited documents, navigate to the Favorites drawer tab.

Expected behavior: nuxeo-favorites displays "You haven't starred documents yet."

Actual behavior: nuxeo-favorites is blank, does not display "You haven't starred documents yet."

Additional Observations:

1. Navigate to any Document.
2. Click on "Add to Favorites" icon.
3. Click on "Remove from Favorites" icon.
4. The message "You haven't starred documents yet." is shown correctly in the left hand side in the "Favorites" section.
5. Upon hard reload, the "You haven't starred documents yet." message disappears.

(See attached video for reference)