Extra empty paragraph and spacing in the information panel in edit mode

Steps to reproduce:

Edit any page that includes another page like the start page of the help application with the wiki editor.

Expected result:

There is no extra space at the beginning of the "Page Information" panel.

Actual result:

There is empty space at the beginning of the panel:

This is caused by XWIKI-19171 that introduced a UIXP for the panel.