🔧 Issue templates: Convert Advocate to Small Events

This commit converts the Advocate template to a Small Events issue template. The purpose of the Advocate template is unclear and does not reflect what the Fedora Mindshare Committee documents under our policy for small events. Instead of using a confusing team name for the template, this makes the issue template reflect the kind of request that we would receive for someone organizing an event within the $150 USD budget cap allowed for small events.

Additionally, this also introduces many of the questions that are currently used in the "Event Requests" GitLab repo. Issues in that repo are private and are meant to only include data like receipts or info for processing reimbursements. So, it does not make sense for us to ask a lot of questions about the event in a private ticket, when that is meant to happen in the open with the public Fedora Mindshare Committee ticket.