JS1 S3 - unsuitable prep

**Background**
JS1 S3 Prep had some missing timing so I put all those exercises in one single timed exercise. Those have to be reviewed if suitable and then divided into separated into smaller ones.

**Acceptance criteria**

- [ ] suitable exercises
- [ ] appropriate timing

**Responsible**
- @LaraHuzjan

**Aproover**
- @kfklein15

Locate the JS1 S3 Prep exercises referred to in the issue and review how they are currently grouped and timed. Split the single timed exercise into smaller exercises, ensuring the resulting exercises are suitable and have appropriate timing.

Written by the indexing model from the issue text.