Removed android.software.backup from automotive.

Reason: the Backup service doesn't support secondary users.

Test: adb shell pm list features | grep backup || echo NOT_FOUND
Test: atest CtsBackupHostTestCases

Bug: 166339795
Bug: 169341308

Change-Id: I9bf370ac7364725c540e0b9c3acf2d597ea6ab5a