Migrate usages of AppBackupUtils to BackupEligibilityRules

After refactoring AppBackupUtils into BackupEligibilityRules (see the
other linked CL), update the usages throughout the code.

Bug: 161241479
Test: atest UserBackupManagerServiceTest
      atest TarBackupReaderTest
      atest BackupHandlerTest
      atest PerformUnifiedRestoreTaskTest
Change-Id: I2a90c4f5b951fa3e3c564a1065ad10a88cc16273