disable virtio-balloon by default for VirtualMachineRawConfig

So that we don't need to add an LL-NDK API to disable it.

To reduce the impact of this change, I've kept the balloon enabled for
rialto and Trusty even though it is likely not needed.

Test: TH
Bug: 369588412
Change-Id: If22280957d735bd40e86b4d43869a4b70a233cd4
diff --git a/android/virtmgr/src/aidl.rs b/android/virtmgr/src/aidl.rs
index 82a5573..79c7d81 100644
--- a/android/virtmgr/src/aidl.rs
+++ b/android/virtmgr/src/aidl.rs
@@ -787,7 +787,7 @@
             boost_uclamp: config.boostUclamp,
             gpu_config,
             audio_config,
-            no_balloon: config.noBalloon,
+            balloon: config.balloon,
             usb_config,
             dump_dt_fd,
         };