Fix string_access_level of NilClass bug

What does this MR do?

This MR fixes some lines where project_features can be nil. This has caused me lots of grief locally and is the reason behind some 500's in v4/api/projects.

Related to:

• #34367 (closed) (500 in production)
• #34800 (closed) (issue identified locally)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content