qt: do not (over) clip the horizontal albums list view in music artists page

So that the fading edge effect does not clip the view. In fact, it still "clips" but only outside the display margins, which I assume is wanted anyway (see the last paragraph).

Due to the fundamental working of item layering, clipping is inevitable. This is because in order to render an item offscreen, it is necessary to know the boundaries of the offscreen buffer. Well, unless the buffer can have infinite size, which I assume is not technically possible as that would require infinite memory.

As a side note, the vertical artists list view stacked above in the left side, and the playlist stacked above in the right side both have non- opaque background so as to reveal window's background blur effect, but they currently use a hack to not reveal any Qt Quick item rendered behind, and even if this is changed in the future, we still do not want the items in the horizontal view to appear behind. So, having the fading edge effect's clipping is beneficial here. However, if in the future we stop using that said hack, we need to have explicit clipping here even though the fading edge effect clips the view, because the fading edge effect is disabled when neither the beginning nor the end fade is enabled, which may have many reasons including not having enough size to have fading effect, or, the current item is the beginning item (so beginning fade is disabled) and the user hovers the end item (so end fade is disabled).

I think this was already the case up until a while ago, perhaps !5270 (merged) or related merge request changed it.