SimpleScheduledTask pollutes logs by default

### Expected Behaviour

A project generated by the AEM project archetype should include a Scheduler example for reference that does not add any additional log messages by default.

### Actual Behaviour

The Scheduler runs every 30 seconds and a new message is logged every 30 seconds. It is easy for a generated project to overlook this and end up with many unnecessary log messages.

https://github.com/adobe/aem-project-archetype/blob/master/src/main/archetype/core/src/main/java/core/schedulers/SimpleScheduledTask.java#L40

and https://github.com/adobe/aem-project-archetype/blob/master/src/main/archetype/ui.config/src/main/content/jcr_root/apps/__appId__/osgiconfig/config/org.apache.sling.commons.log.LogManager.factory.config~__appId__.cfg.json#L6

Related issue: https://github.com/adobe/aem-guides-wknd/issues/168

Start with SimpleScheduledTask.java and the linked LogManager factory configuration in the archetype. Inspect how the scheduled example and its logging configuration produce the recurring message. Done means a freshly generated project does not add this message every 30 seconds by default; verify the relevant generated files.

Written by the indexing model from the issue text.