Rename the Formula insights

[jannesblobel]

Feature request

Is your feature request related to a problem?

I would like to rename our formula insights, like normal chart insights.

This makes it much easier when we use this function in a complex way, and it looks ugly with the name in the table " Formula A + B

Describe the solution you'd like

The pen tool, as in a normal diagram, solves this problem very well.

Describe alternatives you've considered

Additional context

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables]
- [ ] PostHog Hobby self-hosted with `docker compose`, version/commit: [please provide]
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]