Don't notify customers of infra/platform related alerts by default

After internal reflection and based on customer feedback, we’re disabling customer Slack notifications for infra level alerts by default. These are alerts which Skyscrapers is responsible for follow-up, and caused confusion with customers whether they needed to take action or not.

The change will be applied in the coming days. Unless explicitly enabled before, you will stop receiving these types of alerts. However, please get in contact with us if you still wish to receive these alerts after all (for informational purposes).