Because the is "end glow" is when a hyper-dash is *started*, the name was confusing.
The "after-image" was already used in the code as a synonym of "end glow" inconsistently.
It resolves mutual dependency of `Catcher` and `CatcherTrailDisplay`.
Trail generation logic is moved to `Catcher`.
The generation logic no longer uses delayed scheduling because the hidden state is hard to manage.
Instead, the last time a trail is generated is calculated and used.
The new logic has a different behavior when the dash key is pressed in succession under 50ms, but it is not noticeable for normal plays.
This reverts commit 6f2cc5471a and also its testing cases.
This became dead code after actual correct osu!catch skin colouring, we don't support modern skinning (non-legacy skinning) at the moment, so for what it's worth this can be reverted to default red-coloured