Improvements to CSTest : legacy type, wait for LOST, permissions

• Make sure all Agents have a legacy type. This is necessary to
  avoid crashes in LegacyNetworkTracker
• Wait for LOST when disconnecting a network
• Make sure the test package sees its own permissions (importantly
  it can't see background networks otherwise, because it lacks
  CHANGE_NETWORKING_STATE)

Test: in the followup
Change-Id: I9f699b6372a8fe0d5bcd5310d8f35f72e48a6c61

framework/src/android/net/NetworkCapabilities.java

@@ -3235,4 +3235,4 @@ public final class NetworkCapabilities implements Parcelable {
             return new NetworkCapabilities(mCaps);
         }
     }
-}
+}