Prefer status.io to Slack when creating an incident

Why is this change being made?

This change updates the create incident section to prefer creating an incident via status.io over creating it with Slack.

This was prompted by a situation where the Slack method did not work as expected. Upon further investigation, we learned that many folks with experience in the CMOC role strongly prefer using status.io. It's easier to identify when something has gone wrong when using the website and there are more options for customizing the alerts.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added, and the content is SAFE
• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
  • The when to get approval handbook section explains the workflow in more detail
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.
  • I will put this in the SWIR.

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