fix: miscalculation when dragging event with hourStart option (fix #1228)

[adhrinae]

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Description

Fixed the position of the guide element when dragging event with the week.hourStart option.

Resolves #1228

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[heenakwag]

리뷰 완료합니다. 코드는 이견 없습니다.

e2e 테스트 추가하는 건 어떨까요? HourStartOption 스토리도 있으니까 page.goto(HourStartOptionURL);로 URL만 바꾸고 로직은 그대로 테스트 한벌 더 만들면 될 것 같아서요.

[adhrinae]

@dotaitch
테스트 추가할까 하다가 작성하는데 생각보다 오래 걸릴수도 있겠다 싶어서 안했었어요. 그래도 말씀하신김에 간단한 형태로 추가해서 붙일게요.

[lja1018]

리뷰 완료합니다.