panel/JournalView: fix flickering in journal livemode

panel/JournalView: fix flickering in journal livemode

it seems that something changed in extjs 7 which does not quite
restore the correct scroll position when the identical content is set
on a component. this means that sometimes, we update the text
with the identical one, but the scroll position is now off, only
to scroll back to the bottom

this causes a flickering everytime we do the api call.

instead, only update the component when the content really changed.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>