apex: Replace writepid with task_profiles command for cgroup migration

writepid command usage to join a cgroup has been deprecated in favor
of a more flexible approach using task_profiles. This way cgroup path
is not hardcoded and cgroup changes can be easily made. Replace
writepid with task_profiles command to migrate between cgroups.

Bug: 191283136
Test: build and boot
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I40fb9bbd61b36d44b8bb9db118eb83e8218aa81b