CachedAppOptimizer: Replace getAttributePathForTask with CgroupGetAttributePathForTask

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

Change-Id: Ied86a1e13cd3cabbb288a5d63a73556a5559c935
Merged-In: I3d210caa7b15c24eaf523207e4905b20a2894260