Fix downgrade wallpaper restore bug

Add a check in TarBackupReader to enable the restore of packages in the V_To_U_Allowlist in the V to U downgrade scenario

Bug: 341732443
Test: atest -v TarBackupReaderTest, manual test (details: https://b.corp.google.com/issues/341732443#comment18)
Change-Id: I12a1f272b17a12abb532a98c0d93f0a9854fcb51
3 files changed