Meters don't record anything of value

When we create a new op we get the current time and then set a defer to run which is record time.Now() - start into the registered meter. This means that every duration recorded is near instant - gocbcore is callback operated so defer isn't going to work. Note, this doesn't impact gocb at all, metering gocb side is entirely performed by gocb and it does not register a meter with gocbcore.