Split up and deduplicate JS2W4 tasks

https://curriculum.codeyourfuture.io/js2/sprints/4/day-plan/#public-speaking-and-circles-of-influence right now has 5 tabs:
* PD Session
* Power Poses (see also https://github.com/CodeYourFuture/CYF-PD/issues/39)
* Public Speaking
* Circles of Influence
* Create groups for JS3

Below on the same page, there's also a [Create groups for JS3](https://curriculum.codeyourfuture.io/js2/sprints/4/day-plan/#create-groups-for-js3) block.

I think we should:
1. Split up the "Public Speaking" and "Circles of Influence" blocks - there are two separate exercises and combining them makes them harder to understand. It's fine if they go one after the other.
2. Delete the create groups tab - this is already present below. Also, as there is group work in the tech side of JS3, we should make clear that these are separate from the JS3 tech pairings we're going to set up.