fix for #4614 breaks error handler using Zend\Log

In #4616 problem was reintroduced with calling Zend\Stdlib\ErroHandler::start/stop() one level deeper than it was removed from in #2330 - when we tried to use default Zend\Log\Logger::registerErrorHandler() it only logs first php error.
We are using LogWriterStream and after some testing and searching even with $stream_writer->setConvertWriteErrorsToExceptions(false); but tracking showed, that another calls to Zend\Stdlib\ErrorHandler occurs in formatter which was added later.