libcompositionengine: Link against libprocessgroup_util

Not sure why libcompositionengine is linking against libprocessgroup
statically, but now that libprocessgroup_util is a static library
dependency of libprocessgroup, it is not linked against transitively,
so it needs to be included here.

Bug: 349105928
Test: m
Change-Id: Id49f1db65c79bccddf56d7b2ae9edec50e06c831