ResolveField 중복 호출 수정

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Describe the problem and solution

admin 서버 내의 problem.service.ts 및 problem.resolver.ts 중 ResolveField 및 prisma include로 인한 DB 중복호출 건을 수정합니다.

Validations

• [X] Follow our Code of Conduct
• [X] Read the Contributing Guidelines
• [X] Check that there isn't already an issue