[maint] Simplify and change format of the event new issue template

[GeorgianaElena]

This is how it looks rendered https://github.com/GeorgianaElena/.github/issues/new?assignees=&labels=event&projects=&template=event.yml&title=%5BEVENT%5D+%7B%7B+HUB+NAME+%7D%7D

While opening this recent event issue, I realized that our issue template for new events is not matching current expectations:

• support triagers are the ones that open these type of issues now and not communtiy reps
• we do not encourage creating separate node-pools before events anymore, and altough we still don't have clear documentation about events, I figured we should remove it entirely to not cause confusion.
  • although it might make sense to add separate nodepools for hubs with events on shared clusters 🤔 https://infrastructure.2i2c.org/howto/features/dedicated-nodepool/
• we don't ask for feedback from the communities consistently and we don't do anything with that feedback yet, so I removed it. Also, since the communication should happen on support, this feedback questionare I believe should be stored as a template ticket in freshdesk instead.

Follow-up taks after merging this PR:

• Move the feedback request in a template in freshdesk instead -> https://2i2c.freshdesk.com/a/admin/canned_responses/folders/80000143608/responses/80000361132/edit
• Follow-up issue about moving the Engineer task list from the issue template to the infra docs, where some reasoning about creating a separate nodepool on a shared cluster and resource allocation strategies could be added. [Documentation] Add a checklist to decide if infrastructure needs to be updated before an event #3476

[consideRatio]

I agree with the decisions motivated in the PR description, and this seems like a great incremental improvement!