Move learn gitlab svgs to ee

What does this MR do and why?

Related to #461244 (closed)

The four remaining svgs are only used by learn gitlab in ee here, so moving them to the ee directory.

The one svg that's being removed was introduced in !58688 (merged), that page was removed in !152098 (merged), so not used anymore.

How to test locally

1. Setup to simulate SaaS and restart GDK
2. Register as a new user.
3. On /users/sign_up/welcome, select any 'role' and 'Just me' in the welcome form after sign up step.
4. Choose 'Create a new project'
5. Click 'Continue'
6. Fill out fields to create a group and project on the next page.
7. Click 'Create project'
8. Now you should be in "Learn GitLab".

MR acceptance checklist

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