Errcheck issues fixed in server/channels/api4/brand.go (#28362)

* errcheck proper error handling

* write response err check log

* resolving conflicts and io.Copy error handling

server/.golangci.yml

@@ -61,7 +61,6 @@ issues:
       path: "\
         channels/api4/apitestlib.go|\
         channels/api4/bot_test.go|\
-        channels/api4/brand.go|\
         channels/api4/channel.go|\
         channels/api4/channel_test.go|\
         channels/api4/cloud.go|\