Replace use of ro.monkey with ro.test_harness.

Bug 3329873

Change-Id: Ia681803c3d0b0afeceb178b8314c9d7227d99355
diff --git a/tools/labpretest/labpretest.sh b/tools/labpretest/labpretest.sh
index 62238f0..5db7960 100755
--- a/tools/labpretest/labpretest.sh
+++ b/tools/labpretest/labpretest.sh
@@ -531,8 +531,8 @@
   #preping device for monkey run
   log_print "setting adb root"
   adb_command root
-  log_print "setting ro.monkey property"
-  adb_command shell setprop ro.monkey 1
+  log_print "setting ro.test_harness property"
+  adb_command shell setprop ro.test_harness 1
 
   log_print "waiting for device to finish booting"
   result=$($ADB -s $device shell getprop dev.bootcomplete)