Add a dedicated Mainline Test Mapping group for Connectivity modules

Test of *all* Mainline modules are currently configured in a single
`mainline-presubmit` Test Mapping group. This requires that users indicate the
module to install in every entry and is quite tedious.

The above approach also adds overhead due to installing, checking for, and
uninstalling Mainline modules between test module executions. This eats up
precious presubmit time and gets runtimes close to violating the SLO.

This change moves all Connectivity Mainline module tests into a
dedicated Test Mapping group that installs the Mainline module once before
executing all test modules. This also simplifies the configuration syntax by no
longer requiring brackets that indicate the, now implicit, Mainline module.

Bug: 328102821
Test: presubmit checks
Change-Id: Id26725a5a8ff4c76b7cb18fda6022e137f9d8fcf
index 46ade58..ab50478 100644
@@ -1,4 +1,25 @@
+  "captiveportal-networkstack-resolve-tethering-mainline-presubmit": [
+    // These are unit tests only, so they don't actually require any modules to be installed.
+    // We must specify at least one module here or the tests won't run. Use the same set as CTS
+    // so in theory the infra would not need to reinstall/reboot devices to run both.
+    {
+      "name": "NetworkStackTests"
+    },
+    // This is used to verify NetworkStackRootTests with all latest modules listed below on
+    // preivous OS platforms.
+    {
+      "name": "NetworkStackRootTests"
+    }
+  ],
+  "captiveportal-networkstack-mainline-presubmit": [
+    // This is used to verify NetworkStackRootTests with latest CaptivePortalLoginGoogle.apk
+    // but with other modules on different version(e.g. an older tethering module to verify
+    // backwards compatibility of APIs).
+    {
+      "name": "NetworkStackRootTests"
+    }
+  ],
   "presubmit": [
       "name": "NetworkStackTests"