The reasoning is explained in the inline comment, but basically this was
getting blocked by `isPaused` being in an initial `true` state (as it is
on construction), while the source clock was still `IsRunning`.
There's no real guarantee of sync between the source and the `isPaused`
bindable right now. Maybe there should be in the future, but to restore
sanity, let's ensure that a call to `Reset` can at least stop the track
as we expect.
`TestLastPlayedUpdated` was implicitly relying on running first.
`TestGuestScoreIsStoredAsGuest` showing up changed test ordering,
causing the former test to fail if it didn't get to run first.