Optimize remaining IssueNode resolvers

**Is your feature request related to a problem? Please describe.**
I found the organization_name, pull_requests, and task_deadline resolvers were not optimized.

**Describe the solution you'd like**
Optimize these resolvers

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Are you going to work on implementing this?**

- [x] Yes
- [ ] No

**Additional context**
Add any other context or screenshots about the feature request here.