rialto: Add rialto_test to presubmit

Test: TH
Change-Id: Idbea7e2bcaf8b796996dc6adfcdc50a2e37cda0d
diff --git a/rialto/TEST_MAPPING b/rialto/TEST_MAPPING
new file mode 100644
index 0000000..8e3c085
--- /dev/null
+++ b/rialto/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "rialto_test"
+    }
+  ]
+}