libprocessgroup: Fix memcg path for apps

The expected memcg path for apps is
/dev/memcg/apps/uid_<uid>/pid_<pid>.  Right now we are missing the
"apps" component.  Fix it.

Bug: 124776663
Test: Boot on a Go device and does not see error from lmkd anymore.
Change-Id: I0e4c1d8520463fabb171ff4e61479034b6446548
1 file changed