ui: logpanel: catch up to very fast task logs with api calls

ui: logpanel: catch up to very fast task logs with api calls

by updating the start to 'total-limit' if we follow the task log live.
to do that, we decouple the 'scroll' event from updating the 'start'
parameter and call that directly after we scrolled down.

to not trigger the scroll event multiple times, suspend the scroll event
while doing that.

while we're touching those lines, remove the 'setTimeout' workaround
for touchscreens, since it seems to work fine since extjs 7.0

this also fixes the issue that the scroll event is not called sometimes

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