Add NetworkStackModuleTest exclusion for ConnectivityCoverageTests in TEST_MAPPING.

testTetherZeroLengthDhcpPacket requires to install both Tethering
and NetworkStack modules, add NetworkStackModuleTest annotation for
ConnectivityCoverageTests running as presubmit to exclude the
testTetherZeroLengthDhcpPacket from presubmit.

Bug: 287798985
Test: TH
Change-Id: I2e21e2623b181e678189ca7758210be1b5409ae7

TEST_MAPPING

 {
   "presubmit": [
     {
-      "name": "ConnectivityCoverageTests"
+      "name": "ConnectivityCoverageTests",
+      "options": [
+        {
+          "exclude-annotation": "com.android.testutils.NetworkStackModuleTest"
+        }
+      ]
     },
     {
       // In addition to ConnectivityCoverageTests, runs non-connectivity-module tests