Add connectivity pre-check for CtsNativeNetDnsTestCases

This test is run by resolver MTS and it should pre-check device
connectivity before running. The reason why the test never or
seldom failed in the past is probably that it usually ran after
CtsNetTestCasesLatestSdk DnsResolverTest (which is also run by
resolver MTS) that already pre-checked the connectivity.

Bug: 291495329
Test: atest CtsNativeNetDnsTestCases
Change-Id: I20159029c7e68e9c21dcb6e7bbf221cda39117a5

tests/cts/net/native/dns/Android.bp

@@ -30,6 +30,7 @@ cc_defaults {
     ],
     // To be compatible with R devices, the min_sdk_version must be 30.
     min_sdk_version: "30",
+    host_required: ["net-tests-utils-host-common"],
 }
 
 cc_test {

tests/cts/net/native/dns/AndroidTest.xml

@@ -24,6 +24,8 @@
         <option name="push" value="CtsNativeNetDnsTestCases->/data/local/tmp/CtsNativeNetDnsTestCases" />
         <option name="append-bitness" value="true" />
     </target_preparer>
+    <target_preparer class="com.android.testutils.ConnectivityTestTargetPreparer">
+    </target_preparer>
     <test class="com.android.tradefed.testtype.GTest" >
         <option name="native-test-device-path" value="/data/local/tmp" />
         <option name="module-name" value="CtsNativeNetDnsTestCases" />