[NTOS:CM] Avoid unnecessary ObDereferenceObject when handling an ObInsertObject failure (#6673)

In case of failure, ObInsertObject itself dereferences the object, so calling ObDereferenceObject one more time in the failure handler is redundant.

- Remove ObDereferenceObject call from CmpCreateRegistryRoot in case ObInsertObject fails.
- Add missing RootKey dereference if CmpCreateRegistryRoot failed to get the key cell (KeyCell).

CORE-17904

ntoskrnl/config/cmsysini.c

@@ -1109,7 +1109,11 @@ CmpCreateRegistryRoot(VOID)
     /* Sanity check, and get the key cell */
     ASSERT((&CmiVolatileHive->Hive)->ReleaseCellRoutine == NULL);
     KeyCell = (PCM_KEY_NODE)HvGetCell(&CmiVolatileHive->Hive, RootIndex);
-    if (!KeyCell) return FALSE;
+    if (!KeyCell)
+    {
+        ObDereferenceObject(RootKey);
+        return FALSE;
+    }
 
     /* Create the KCB */
     RtlInitUnicodeString(&KeyName, L"\\REGISTRY");
@@ -1144,7 +1148,6 @@ CmpCreateRegistryRoot(VOID)
                             &CmpRegistryRootHandle);
     if (!NT_SUCCESS(Status))
     {
-        ObDereferenceObject(RootKey);
         return FALSE;
     }