libprocessgroup: Combine all 3 ActivateControllers implementations into one

Remove this code duplication and use just one interface.

Bug: 349105928
Change-Id: Id8c7186d9665e9087a654f5781b7593b06349160
diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index 83a2258..d3719ee 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -662,10 +662,9 @@
         return -errno;
     }
     if (activate_controllers) {
-        ret = CgroupMap::GetInstance().ActivateControllers(uid_path);
-        if (ret) {
-            LOG(ERROR) << "Failed to activate controllers in " << uid_path;
-            return ret;
+        if (!CgroupMap::GetInstance().ActivateControllers(uid_path)) {
+            PLOG(ERROR) << "Failed to activate controllers in " << uid_path;
+            return -errno;
         }
     }