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.
I'm not sure what the cause of the issue is, but I'm also not sure why
it wasn't using `DrawablePool` (was it not around back then?).
Either way, switching to a proper pool fixes things just fine.
Resolves https://github.com/ppy/osu/issues/25009.