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/app2/Android.bp b/tests/cts/hostside/app2/Android.bp
index 3dde3ff..cb55c7b 100644
--- a/tests/cts/hostside/app2/Android.bp
+++ b/tests/cts/hostside/app2/Android.bp
@@ -36,5 +36,5 @@
         "sts",
     ],
     sdk_version: "test_current",
-    min_sdk_version: "31",
+    min_sdk_version: "30",
 }