CachedAppOptimizer: Replace getAttributePathForTask with CgroupGetAttributePathForTask

getAttributePathForTask has always directly called
CgroupGetAttributePathForTask, and there is no reason for callers not to
use CgroupGetAttributePathForTask.

Test: m
Flag: EXEMPT refactor
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f5f805789787ad28a8334fdf9aa1c2e1c2958a27)
Merged-In: I3d210caa7b15c24eaf523207e4905b20a2894260
Change-Id: I3d210caa7b15c24eaf523207e4905b20a2894260