refactor(be): admin problem and submission exception handling

[mnseok]

Description

에러 핸들링 부분을 resolver에서 service 부분으로 옮겼습니다.

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• [ ] Read the Contributing Guidelines
• [ ] Read the Contributing Guidelines and follow the Commit Convention
• [ ] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• [ ] Ideally, include relevant tests that fail without this PR but pass with it.