Updates the "Task" issue template
- Removes the required input of "Have you searched for similar issues?"
- Makes the tasks body a required input
Removing the "Have you searched for similar issues?" because this
template is used mostly internally for incremental issues towards a
project / epic and not used by the community
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## Summary by CodeRabbit
- **Documentation**
- Updated the issue template by removing the checkbox for checking
existing issues.
- Modified the 'SubTasks' field from a text area to a mandatory checkbox
list in the issue template.
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