Create ArtifactPath function to abstract test paths

When AOS is included as an external repo and renamed, paths have to be
updated.  Make a function to handle all this.

Change-Id: If1dfbfb3191809d86da1dca92981b7a0b851c51f
diff --git a/aos/network/message_bridge_test.cc b/aos/network/message_bridge_test.cc
index 3798943..1953dc2 100644
--- a/aos/network/message_bridge_test.cc
+++ b/aos/network/message_bridge_test.cc
@@ -8,6 +8,7 @@
 #include "aos/network/message_bridge_client_lib.h"
 #include "aos/network/message_bridge_server_lib.h"
 #include "aos/network/team_number.h"
+#include "aos/testing/path.h"
 #include "aos/util/file.h"
 #include "gtest/gtest.h"
 
@@ -19,6 +20,8 @@
 namespace message_bridge {
 namespace testing {
 
+using aos::testing::ArtifactPath;
+
 namespace chrono = std::chrono;
 
 std::string ShmBase(const std::string_view node) {
@@ -49,7 +52,7 @@
  public:
   MessageBridgeParameterizedTest()
       : config(aos::configuration::ReadConfig(
-            absl::StrCat("aos/network/", GetParam().config))),
+            ArtifactPath(absl::StrCat("aos/network/", GetParam().config)))),
         pi1_boot_uuid_(UUID::Random()),
         pi2_boot_uuid_(UUID::Random()) {
     util::UnlinkRecursive(ShmBase("pi1"));