Whitelist com.android.perftests.core in am instrument.

Test is using private APIs.

Bug: 64382372
Bug: 74963051
Bug: 76162083
Test: make
Change-Id: I053b89327944e3722f2c11a9bc83ed1676fa9f85

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -21798,6 +21798,8 @@ public class ActivityManagerService extends IActivityManager.Stub
         "com.android.frameworks.locationtests",
         "com.android.frameworks.coretests.privacy",
         "com.android.settings.ui",
+        "com.android.perftests.core",
+        "com.android.perftests.multiuser",
     };
 
     public boolean startInstrumentation(ComponentName className,