Move cts/net/TEST_MAPPING to toplevel

The tests should just be run on any change in packages/modules/Connectivity,
not just changes in the CTS package.

Change-Id: I1c86c402f39a8a9b84e7422445df289c3ea7842f
Test: TEST_MAPPING needs to be verified by TH
diff --git a/tests/cts/net/TEST_MAPPING b/TEST_MAPPING
similarity index 88%
rename from tests/cts/net/TEST_MAPPING
rename to TEST_MAPPING
index 8f65b65..1db4baa 100644
--- a/tests/cts/net/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -1,5 +1,6 @@
 {
-  // TODO: move to mainline-presubmit once supported
+  // Run in addition to mainline-presubmit as mainline-presubmit is not
+  // supported in every branch.
   "presubmit": [
     {
       "name": "CtsNetTestCasesLatestSdk",