CachedAppOptimizer: remove native freezer enabling code

After merging the cgroup v2 uid/pid, processes are handled individually
at freezer enable/disable, and the native freezer enable/disable code is
not mapped to a profile anymore. For this reason all the related code
ought to be removed.

Bug: 181130874
Test: booted, verified freezer proper functioning
Change-Id: Ibd958e7a34cf979c3db3a92d21155de551b00e5a