The test connects finished to the groups clear method, which in turn
deletes the animation instance. Thus, no member must be accessed after
calling stop, unless we use a (costly) QPointer to guard against
deletion.
Notify earlier that totalCurrentTime changed to avoid the issue.
As a drive-by, modernize the connect in the test.
Fixes: QTBUG-94143
Change-Id: I923101107b7f79115be69a58c8e8d5177a98d48f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>