Limit PROJECTS_RECEIVING_REFERRALS picklist to current ds

[gigxz]

Please squash merge this PR

Description

This was incorrectly including projects from other data sources.

Type of change

• [x] Bug fix

Checklist before requesting review

• [x] I have performed a self-review of my code
• [ ] I have run the code that is being changed under ideal conditions, and it doesn't fail
• [x] My code includes comments and/or descriptive variable names to help other engineers understand the intent (or not applicable)
• [x] My code follows the style guidelines of this project (rubocop)
• [x] I have updated the documentation (or not applicable)
• [ ] If it's not obvious how to test this change, I have provided testing instructions in this PR or the related issue