Add trial_registration_hierarchy_education experiment

What does this MR do and why?

• Implements trial_registration_hierarchy_education experiment to enable users to better understand what groups and projects mean.
• Removes deprecated bootstrap code (toggle: 'tab')

References

#579013+

Screenshots or screen recordings

Viewport size	Control	Candidate
mobile
desktop

How to set up and validate locally

1. Simulate SaaS instance
2. Roll out feature flag trial_registration_hierarchy_education for 50% of actors.
3. log out
4. Go to localhost:3000
5. Register new account
6. On next screen select Create new project and Just for me (you might need to try multiple times to hit control and variant)

MR acceptance checklist

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