Bug: Cannot delete interaction steps unless you delete the innermost questions and responses first

[ibrand]

Describe the bug

To Reproduce Steps to reproduce the behavior:

1. Go to the campaign edit page for a campaign that already has an interaction tree
2. Click on interaction steps
3. Try to delete any interaction steps that have nested responses and questions
4. See error:

Error: GraphQL error: delete from "interaction_step" where "id" = $1 - update or delete on table "interaction_step" violates foreign key constraint "interaction_step_parent_interaction_id_foreign" on table "interaction_step"

Expected behavior We should be able to delete interaction steps from any part of the tree.

Platform (please complete the following information):

• OS: MacOS
• Browser Chrome
• Desktop
• Version v7.0 We have also seen this behavior reproduced on a Linux machine