Move statsd TEST_MAPPINGS to statsd root

Changes in statsd need to trigger the tests, not just changes
to the tests themselves.

Bug: 151868293
Test: presubmit
Change-Id: Ia271c07df52da8c765c683457c63e310282f66e5
diff --git a/apex/TEST_MAPPING b/apex/TEST_MAPPING
new file mode 100644
index 0000000..93f1087
--- /dev/null
+++ b/apex/TEST_MAPPING
@@ -0,0 +1,10 @@
+{
+  "presubmit" : [
+    {
+      "name" : "FrameworkStatsdTest"
+    },
+    {
+      "name" : "LibStatsPullTests"
+    }
+  ]
+}