Fix shell command 'list staged-sessions'

After applying visibility to get session info APIs, ROOT_UID should
still be able to list staged-sessions via adb shell.

Bug: 204141763
Test: manually test 'pm list staged-sessions' via adb shell with and
      without root to verify if the result is the same.
Change-Id: I09a8a146be82deba10d3b11deea7a0b344a36c56

services/core/java/com/android/server/pm/PackageManagerService.java

@@ -8914,7 +8914,8 @@ public class PackageManagerService extends IPackageManager.Stub
      * return {@code true} if any one application belongs to the shared user ID meets the criteria.
      */
     boolean canQueryPackage(int callingUid, @Nullable String targetPackageName) {
-        if (targetPackageName == null) {
+        // Since getSettingLPr returns null for ROOT_UID, add an extra check for it here.
+        if (callingUid == Process.ROOT_UID || targetPackageName == null) {
             return true;
         }
         synchronized (mLock) {