Fix GraphQL deprecation reasons

What does this MR do?

This MR corrects two GraphQL deprecation_reason strings:

1. In one deprecation reason, a field is referred to as design_collection. It appears like this within Ruby, but is always expressed by the API as designCollection.
2. In another deprecation reason, capitalized the first letter to be consistent with all other deprecation_reason strings.

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