Headless: fix system update notification

Allow the OTA client from the main user to send OTA information
back to the framework.

Bug: 262854379
Test: GtsDevicePolicyTestCases:PendingSystemUpdateTest
Change-Id: I607e0515dee1bd8ba9d9a68940c13c1a6d147196

services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java

@@ -16549,11 +16549,13 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {
                 hasCallingOrSelfPermission(permission.NOTIFY_PENDING_SYSTEM_UPDATE),
                 "Only the system update service can broadcast update information");
 
-        if (UserHandle.getCallingUserId() != UserHandle.USER_SYSTEM) {
-            Slogf.w(LOG_TAG, "Only the system update service in the system user can broadcast "
-                    + "update information.");
-            return;
-        }
+        mInjector.binderWithCleanCallingIdentity(() -> {
+            if (!mUserManager.getUserInfo(UserHandle.getCallingUserId()).isMain()) {
+                Slogf.w(LOG_TAG, "Only the system update service in the main user can broadcast "
+                        + "update information.");
+                return;
+            }
+        });
 
         if (!mOwners.saveSystemUpdateInfo(info)) {
             // Pending system update hasn't changed, don't send duplicate notification.