[Thread] create standalone border router test module

This is for reduce the overall time of the ThreadNetworkIntegrationTests
which now runs twice for both BR and non-BR cases

Bug: 403360961
Bug: 402480982

Change-Id: Ifa80b8e8885ed980064f92100ef817f9f62b4dc2
diff --git a/thread/TEST_MAPPING b/thread/TEST_MAPPING
index 40842f1..0c38f93 100644
--- a/thread/TEST_MAPPING
+++ b/thread/TEST_MAPPING
@@ -16,6 +16,9 @@
     },
     {
       "name": "ThreadNetworkTrelDisabledTests"
+    },
+    {
+      "name": "ThreadBorderRouterIntegrationTests"
     }
   ]
 }