Making VMS a @SystemAPI

This CL should go in the Pi/Master and O.Car.MR1 branches.
Test: I built an image w/o @FutureFeature enabled and verified all the tests pass. Also fixed a test flakiness.

Change-Id: I50495d6264c7932b670a4fae456d7f89ab5c1e55
diff --git a/car-lib/src/android/car/vms/VmsLayer.java b/car-lib/src/android/car/vms/VmsLayer.java
index 9125796..b921230 100644
--- a/car-lib/src/android/car/vms/VmsLayer.java
+++ b/car-lib/src/android/car/vms/VmsLayer.java
@@ -16,7 +16,7 @@
 
 package android.car.vms;
 
-import android.car.annotation.FutureFeature;
+import android.annotation.SystemApi;
 import android.os.Parcel;
 import android.os.Parcelable;
 
@@ -27,7 +27,7 @@
  *
  * @hide
  */
-@FutureFeature
+@SystemApi
 public final class VmsLayer implements Parcelable {
 
     // The layer Type.