Update BackupEligibilityRules

1. Remove unused appIgnoresIncludeExcludeRules() and associated tests
2. Remove logic for enforcing full backup for apps with k/v agents and
   associated tests
3. Only ignore allowBackup for non-system apps in D2D and guard the
   behavior by target SDK

Bug: 183147249
Test: atest BackupEligibilityRulesTest
Change-Id: Id8b0862dae492de69c553858e27859970278d7db