Makes UM.isUsersOnSecondaryDisplaysSupported() @TestApi

Initially, UM.isUsersOnSecondaryDisplaysEnabled() was marked @TestApi,
but that's an static API meant to be used internally only.

Test: m update-api
Bug: 246003632

Change-Id: Icca31e7b82ffd03645a5cb27af27325c1bfc0bfe
diff --git a/core/api/test-current.txt b/core/api/test-current.txt
index deb5aca..17e43a1 100644
--- a/core/api/test-current.txt
+++ b/core/api/test-current.txt
@@ -1874,7 +1874,7 @@
     method @NonNull @RequiresPermission(anyOf={android.Manifest.permission.MANAGE_USERS, android.Manifest.permission.CREATE_USERS}) public java.util.List<android.content.pm.UserInfo> getUsers(boolean, boolean, boolean);
     method @RequiresPermission(anyOf={android.Manifest.permission.MANAGE_USERS, android.Manifest.permission.CREATE_USERS}) public boolean hasBaseUserRestriction(@NonNull String, @NonNull android.os.UserHandle);
     method public static boolean isSplitSystemUser();
-    method public static boolean isUsersOnSecondaryDisplaysEnabled();
+    method public boolean isUsersOnSecondaryDisplaysSupported();
     method @NonNull @RequiresPermission(anyOf={android.Manifest.permission.MANAGE_USERS, android.Manifest.permission.CREATE_USERS}) public android.content.pm.UserInfo preCreateUser(@NonNull String) throws android.os.UserManager.UserOperationException;
   }
 
diff --git a/core/java/android/os/UserManager.java b/core/java/android/os/UserManager.java
index f6aaee8..1e91700 100644
--- a/core/java/android/os/UserManager.java
+++ b/core/java/android/os/UserManager.java
@@ -2843,7 +2843,6 @@
     /**
      * @hide
      */
-    @TestApi
     public static boolean isUsersOnSecondaryDisplaysEnabled() {
         return SystemProperties.getBoolean("fw.users_on_secondary_displays",
                 Resources.getSystem()
@@ -2853,10 +2852,12 @@
     /**
      * Returns whether the device allows users to run (and launch activities) on secondary displays.
      *
-     * @return {@code false} for most devices, except automotive vehicles with passenger displays.
+     * @return {@code false} for most devices, except on automotive builds for vehiches with
+     * passenger displays.
      *
      * @hide
      */
+    @TestApi
     public boolean isUsersOnSecondaryDisplaysSupported() {
         return isUsersOnSecondaryDisplaysEnabled();
     }