`TransactionIntegration` should always set a transaction

[cleptric]

sentry-php/src/Integration/TransactionIntegration.php

Lines 39 to 43 in 1b9e3b2

	if (isset($hint->extra['transaction']) && \is_string($hint->extra['transaction'])) {
	$event->setTransaction($hint->extra['transaction']);
	} elseif (isset($_SERVER['PATH_INFO'])) {
	$event->setTransaction($_SERVER['PATH_INFO']);
	}

We should make sure we always end up writing something into $event->transaction, to offer a better UX in the product. With my local setup, $_SERVER['PATH_INFO'] seems to be not populated, using Apache.