Some project admin roles are missing PROJECT_ADMIN_PAGE read permission

**Symptom**

Some existing project admin roles do not have the PROJECT_ADMIN_PAGE read permission, while others do. Affected roles behave as if they lack project admin page access.

**Suspected cause**

A data migration appears to have missed backfilling the PROJECT_ADMIN_PAGE read permission for all existing project admin roles, leaving a subset without it.

JIRA Issue: BA-6844

Start by locating the data migration and permission definitions for PROJECT_ADMIN_PAGE, then inspect how existing project-admin roles are populated. Done means every existing project-admin role has the permission and a regression check covers the backfill.

Written by the indexing model from the issue text.