Add CtsNetTestCasesLatestSdk to postsubmit

Also exclude some tests that cannot run on cuttlefish.
This is a first step to add the suite to presubmit. Having the test in
presubmit is essential to avoid regressions and keep it passing.

Bug: 158153057
Test: m CtsNetTestCases; this patch will provide postsubmit results
Change-Id: I48b2b5490d3fd5eb6f9456825c11f3fee0ec5b67
diff --git a/tests/cts/net/TEST_MAPPING b/tests/cts/net/TEST_MAPPING
new file mode 100644
index 0000000..e2a9c75
--- /dev/null
+++ b/tests/cts/net/TEST_MAPPING
@@ -0,0 +1,13 @@
+{
+  // TODO: move to mainline-presubmit once supported
+  "postsubmit": [
+    {
+      "name": "CtsNetTestCasesLatestSdk",
+      "options": [
+        {
+          "exclude-annotation": "com.android.testutils.SkipPresubmit"
+        }
+      ]
+    }
+  ]
+}