Simplify Grid scroll handling. (#11835)

Simplify Grid scroll handling. (#11835)

If first attempt at scrolling doesn't succeed it's unlikely that
continuing to wait is going to make any difference. Cache should be
populated before triggering any actions that depend on the row being
visible, otherwise it should be enough to trust that scrollToRow
actually scrolls to row and once scrolling is done the row is as much in
view as it's going to get. This way we don't get into a situation where
Editor never opens because it's still waiting for that one last pixel
that can't be achieved thanks to browser zoom causing rounding errors.

Continues on #11672