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/aidl/Android.bp b/tests/cts/hostside/aidl/Android.bp
index 8ec9284..31924f0 100644
--- a/tests/cts/hostside/aidl/Android.bp
+++ b/tests/cts/hostside/aidl/Android.bp
@@ -20,7 +20,7 @@
 java_test_helper_library {
     name: "CtsHostsideNetworkTestsAidl",
     sdk_version: "current",
-    min_sdk_version: "31",
+    min_sdk_version: "30",
     srcs: [
         "com/android/cts/net/hostside/*.aidl",
         "com/android/cts/net/hostside/*.java",