Don't run lang.ThreadGroup.suspend.ThreadGroup_suspend_A01 on cf backend

It is haning the bot.

Change-Id: I677ff9ee571860b22c6fadf236194716578e0d14
diff --git a/src/test/java/com/android/tools/r8/JctfTestSpecifications.java b/src/test/java/com/android/tools/r8/JctfTestSpecifications.java
index 4e61335..079c89c 100644
--- a/src/test/java/com/android/tools/r8/JctfTestSpecifications.java
+++ b/src/test/java/com/android/tools/r8/JctfTestSpecifications.java
@@ -1863,6 +1863,7 @@
               "lang.Runtime.execLjava_lang_String_Ljava_lang_StringLjava_io_File.Runtime_exec_A04",
               anyDexVm())
           .put("lang.Thread.getContextClassLoader.Thread_getContextClassLoader_A02", anyDexVm())
+          .put("lang.ThreadGroup.suspend.ThreadGroup_suspend_A01", cf())
           .put("lang.ThreadGroup.suspend.ThreadGroup_suspend_A02", anyDexVm())
           .put("lang.Thread.setDaemonZ.Thread_setDaemon_A03", anyDexVm())
           .put("lang.ProcessBuilder.environment.ProcessBuilder_environment_A07", anyDexVm())