Automated cron runs should only be enabled by default for Standard profile

Problem

• After installing Drupal with the Minimal profile, automated cron runs were automatically enabled.

Details

• Automated cron runs (via JS/Ajax) only exist for low-end sites on shared hosting and such, which may not have access to a real crontab.
• The feature should be an opt-in, instead of an opt-out.

Proposed solution

1. Change the default value of system.cron:threshold.autorun to 0.
2. Add a config file to Standard profile that configures system.cron:threshold.autorun with the current default value.