Further protect app private data files

Remove the special case that allowed init to relabel app_data_file and
privapp_data_file. The auditallow added in
ab82125f has never triggered.

Bug: 80190017
Test: policy compiles
Test: no SELinux denials collected for the auditallow rule
Change-Id: Ide7c31e1a0628464ec2fcf041e8975087c39166d