ui: logpanel: fix glitching fast task logs

ui: logpanel: fix glitching fast task logs

if the total we got was bigger than the last line number, we appended
empty lines at the end of the panel, to which we scrolled

the only time we need to do that is when we do not follow the task log
'live' but when we are elsewhere (to keep the scroll position/size)

so give the lines directly to 'updateView' and let it decide
if we append the empty lines at the end

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