Remove Tunables for QSAnimator, and add some documentation on what the class does.

Specifically, use the default value of `true` for both `sysui_qs_fancy_anim` and `sysui_qs_move_whole_rows`, and simplify the code accordingly.

There are no mentions of these flags in the codebase or are recommended for Android Go (https://docs.partner.android.com/gms/building/go/config-guide-13), so lets remove this static config values and we can reduce the mental load of engineers working with this code.

Test: Manual and tests still pass
Bug: 203537805
Change-Id: I9a0ff9c1daf538bee26967b764faa7210b1ad2fa