Fix default visibility_level for new projects

What does this MR do?

Changes the default value for the project visibility level to Gitlab::CurrentSettings.default_project_visibility, which means that it can be configured in the Admin interface of GitLab.

This fixes #45779 (closed) (As long as the "Default project visibility" is not restricted)

What are the relevant issue numbers?

Fixes #45779 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer