Remove maxTargetSdk from APIs used by backup

The D2D backup process Source backup currently uses
FullBackup.backupToTar; restricting it breaks (at least) SMS transfer.
Remove the constraint, for now.

Bug: 172049974
Test: Automated backup test runs before submission
Change-Id: I67012521e57bb6cadd76bedea1d7415359f2aaf7
1 file changed