JS3 Sprint 4 - update timings and coursework

**What type of request is it**
- [ ] New content
- [x] Update/additional content

**Is the change on:
- [x] Prep
- [x] Day-plan
- [x] Coursework

**Why do you want to suggest this update?**
Feedback from NW6 is that the PD content has time estimations that they cannot fulfil. They also mentioned that most of our coursework is set as mandatory, which it shouldn't.

**Timing process suggestion**
- [ ] Open the current content (intro, prep, exercise, coursework)
- [ ] Paste it into your AI of preference, asking how long someone with a B2 level of English would take to read this
- [ ] Use the slowest or average + X%
- [ ] Update the timing accordingly
- [ ] Review what other content/exercise must be removed

**Coursework**
Per sprint we should have

- 1 key coursework
- 1 Mandatory coursework
- Rest should be stretch coursework

**Document necessary changes as a comment**
- Changes should be done in CMS by the volunteres
- Coursework change will be done by @kfklein15
- Must be changed on Module Coursework, CMS and Test Coursework for PD Milestone