Extend CtsHostsideNetworkTests support to Android R (API 30)

Updated the testing app and AIDL interface used by
CtsHostsideNetworkTests to support min_sdk_version 30, ensuring
compatibility with Android R devices.

Test: TH
Change-Id: Ib334f95cf9bd199cce46b2c98d40d8361179aac3
diff --git a/tests/cts/hostside/app/Android.bp b/tests/cts/hostside/app/Android.bp
index 798cf98..40cabc4 100644
--- a/tests/cts/hostside/app/Android.bp
+++ b/tests/cts/hostside/app/Android.bp
@@ -44,7 +44,7 @@
         "general-tests",
         "sts",
     ],
-    min_sdk_version: "31",
+    min_sdk_version: "30",
 }
 
 android_test_helper_app {