Revert^2 "Make sure all runtime threads are in the System thread group."

This reverts commit 9ca8b2bf46978e3a5698f8a27b48aa7eff3514df.

The test 2005 exposed an ABA race which could cause the test to
sometimes fail with CHECK failures or GC corruption.

Reason for revert: Fixed issue causing ABA race in PreObjectAlloc with
                   test.
Test: ./test.py --host --debug-gc
Bug: 146178357

Change-Id: If265f765e0c1e692755904b4c40bbc718d98f065
diff --git a/test/Android.bp b/test/Android.bp
index de2ab3f..0051853 100644
--- a/test/Android.bp
+++ b/test/Android.bp
@@ -361,6 +361,7 @@
         "1974-resize-array/resize_array.cc",
         "1975-hello-structural-transformation/structural_transform.cc",
         "1976-hello-structural-static-methods/structural_transform_methods.cc",
+        "2005-pause-all-redefine-multithreaded/pause-all.cc",
     ],
     // Use NDK-compatible headers for ctstiagent.
     header_libs: [