Before this PR clicking on all series toggled them to "on" but then clicking a series again toggle just that series "off". This felt misleading because clicking all fo the series "on" implies resetting the chart to the default state. Such that clicking a series from here, should only display that series.
This PR clears out the selections when all series have been "toggled on" so that the default state is reset correctly.
Test plan
Added unit test confirming deselecting of series when all series have been selected
