CTS: Add vm-tests presubmit

Add TEST_MAPPING with presubmit.

Test: pushd cts/tools/vm-tests-tf && atest && popd
Change-Id: Ic5963628307edaedcf7eb0fbf95632ba0bcc1146
diff --git a/tools/vm-tests-tf/TEST_MAPPING b/tools/vm-tests-tf/TEST_MAPPING
new file mode 100644
index 0000000..a566107
--- /dev/null
+++ b/tools/vm-tests-tf/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "vm-tests-tf"
+    }
+  ]
+}