Kill its process group even if the given process is already dead

So the child processes in the process group won't be orphaned
when we decide to kill the process group of a given process but
find it's already dead.

Bug: 266633286
Test: atest MicrodroidDemoApp
Change-Id: Ib6f45b992566f0ab5cf152463c95294a306dd736
1 file changed