Update ways to identify if request submitted directly

Why is this change being made?

This change updates how to look out for an account deletion issue that is created via form, or through user sending an email via the Personal Account Requests Service Desk email address. The previous way of identifying seems to be invalid now ("Requests submitted using the form will have techsupport@gitlab.com as the issue creator."), as reviewing the new valid issues created, they are still created by via GitLab Support Bot.

This change is important because it helps determine whether or not the issue is to be closed, and for us to direct users to the correct method (form submission) to create the account deletion request.

Based on the conversation with @izzyfee on Slack, there are 2 ways (added in MR) to tell whether the issue was created via a form or by sending an email:

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