Fixes#14491.
When a screensharing participant leaves and is unmuted or sharing the tab audio, there is a dominant speaker changed event which stores wrong values in filmstrip state. And because we skip reordering when there is no filmstrip scroll and no screensharers to avoid reordering on every dominant speaker event for small meetings, we fail to evaluate that the screensharere is actually gone and we still show it.
This will not happen if the one sharing is not dominant speaker (muted) or if there are more participants in the meeting (there is a scroll).
