[nearby][clean up] Delete all Fast Pair AOSP and HalfSheetUX code

Test: -m
Fix: 292812342
Fix: 297413048
Fix: 214879640
Ignore-AOSP-First: merge conflicts, need to be merged in downstream first
Change-Id: I7efa92469f0c061a972a7dadf6a38686b78c61b4
Merged-In: I7efa92469f0c061a972a7dadf6a38686b78c61b4
540 files changed