Replace Repeater with ListView for task group list

Unlike Repeater ListView loads only visible items.
This behaviour leads to huge performance improvement.
ListView also requires to set width and height explicitly.

One remaining issue is time of displaying tooltips.
Tooltips are displayed only for short amount of time.
With Repeater this timer starts after tooltip is displayed.
With ListView it looks like timer starts while ListView is preparing to display,
which may lead to situation when timer fires before tooltip is displayed,
thus when tooltip is ready, it is briefly displayed and immediately hidden again.

BUG: 433907