Do not save crop hints to preferences (1/3)

Since we can get the currently set wallpaper's crop hints from the
wallpaper manager, there is no need to save the crop hints in the
prefereces, which may cause misalignment with the single source of
truth.

Saving information in the preferences is needed in 2 condition:
1. The information is not kept by the wallpaper manager
2. The information is needed for snapshot logging

Test: Manually tested it works as before
Bug: 309139122
Flag: ACONFIG com.android.wallpaper.multi_crop_preview_ui_flag DEVELOPMENT
Change-Id: Ia83764f55957f425448ec857a1e9db23176eada9