[fuchsia] move binaries out of /system

Change-Id: Ie04ccad8de026cfe5734d72edfb3c07832009d53

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index 4deaa91..c7a02b4 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -30,7 +30,6 @@
 
 package("asio_unittests") {
   testonly = true
-  deprecated_system_image = true
 
   deps = [
     ":tests",