Move topic metadata in two more places

Topic metadata is potentially large and slow to copy, so this change
moves it in a couple of places we weren't moving it before which
showed up in a large load test profile.

src/v/kafka/server/handlers/metadata.cc

@@ -158,15 +158,17 @@ create_topic(request_context& ctx, model::topic&& topic) {
               metadata_response::topic t;
               t.name = std::move(res[0].tp_ns.tp);
               t.error_code = map_topic_error_code(res[0].ec);
-              return ss::make_ready_future<metadata_response::topic>(t);
+              return ss::make_ready_future<metadata_response::topic>(
+                std::move(t));
           }
           auto tp_md = md_cache.get_topic_metadata(res[0].tp_ns);
 
           if (!tp_md) {
               metadata_response::topic t;
               t.name = std::move(res[0].tp_ns.tp);
               t.error_code = error_code::invalid_topic_exception;
-              return ss::make_ready_future<metadata_response::topic>(t);
+              return ss::make_ready_future<metadata_response::topic>(
+                std::move(t));
           }
 
           return wait_for_topics(