Remove references to the ast_type_traits namespace

Follow up to cd62511496938e33c061c90796dd23a5288ff843 /
https://reviews.llvm.org/D74499

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D92994
diff --git a/clang-tools-extra/clang-query/Query.h b/clang-tools-extra/clang-query/Query.h
index 223644f..4c95195 100644
--- a/clang-tools-extra/clang-query/Query.h
+++ b/clang-tools-extra/clang-query/Query.h
@@ -120,7 +120,7 @@
   static const QueryKind value = QK_SetOutputKind;
 };
 
-template <> struct SetQueryKind<ast_type_traits::TraversalKind> {
+template <> struct SetQueryKind<TraversalKind> {
   static const QueryKind value = QK_SetTraversalKind;
 };