[MM-61105] Fix errcheck linter errors in config_test.go (#30689)

server/.golangci.yml

@@ -90,7 +90,6 @@ issues:
         channels/api4/websocket_test.go|\
         channels/app/bot_test.go|\
         channels/app/brand.go|\
-        channels/app/config_test.go|\
         channels/app/file.go|\
         channels/app/file_test.go|\
         channels/app/helper_test.go|\