XWIKI-22488: Editing the paragraph using the In-place editor moves the display...

XWIKI-22488: Editing the paragraph using the In-place editor moves the display window to the bottom/top of the page
* There were two issues:
** when editing a section inplace, we were removing the tabindex attribute from the editable area too early, and since the realtime plugin puts the editable area in read-only mode while it connects to the realtime session, the focus was lost (to keep the focus the editable area needs to either be editable or have the tabindex attribute set)
** when connecting to the realtime session, the realtime plugin was displaying an information box at the top of the page and it was scrolling it into view

(cherry picked from commit 9fb3d668)