fix(fe): differentiate sample and user id

[juhyeong0505]

Description

User testcase id와 기존에 존재하던 Sample testcase id가 함께 관리되어 발생하는 id문제를 해결하였다. 예로, Sample testcase가 2개 추가된 상태에서 User testcase를 추가하면 #3번째 id가 부여되는 문제를 User testcase는 따로 #1부터 시작하도록 하였다.

Additional context

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closes TAS-1057

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• [x] Read the Contributing Guidelines
• [x] Read the Contributing Guidelines and follow the Commit Convention
• [x] 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.