Reduce ERROR notifications for certain "normal" metadata scenarios (i.e. 404)

[valentijnscholten]

Current Behavior

I noticed that every non 2xx http response code triggers an ERROR notification to be raised for metadata analysis:

dependency-track/src/main/java/org/dependencytrack/tasks/repositories/AbstractMetaAnalyzer.java

Lines 78 to 89 in 45982a2

	protected void handleUnexpectedHttpResponse(final Logger logger, String url, final int statusCode, final String statusText, final Component component) {
	logger.debug("HTTP Status : " + statusCode + " " + statusText);
	logger.debug(" - RepositoryType URL : " + url);
	logger.debug(" - Package URL : " + component.getPurl().canonicalize());
	Notification.dispatch(new Notification()
	.scope(NotificationScope.SYSTEM)
	.group(NotificationGroup.REPOSITORY)
	.title(NotificationConstants.Title.REPO_ERROR)
	.content("An error occurred while communicating with an " + supportedRepositoryType().name() + " repository. URL: " + url + " HTTP Status: " + statusCode + ". Check log for details." )
	.level(NotificationLevel.ERROR)
	);
	}

Proposed Behavior

I propose to make this less noisy. The logging is already on DEBUG level, maybe the notification should be on DEBUG as well. At least for 404 which can be quite normal, at least for the Composer Package Repository (#4470)
Maybe other 4xx and 5xx errors could/should trigger WARN or ERROR.

Checklist

• I have read and understand the contributing guidelines
• I have checked the existing issues for whether this enhancement was already requested