[Server][Fix] /mypage selections 구현

### ISSUE
- Group: `server`
- Type: `fix`
- Detail: `/mypage` 내 selections 들도 표시되도록 구현

### TODO
1. [ ] `/searchselections` 활용

### Estimated time

### `3h`

### Labels
- Estimated time: `E: 3h`
- Group : `server`
- Sprint: `Sprint 5 : My Page`
- Urgency: `High`
