fix(chat:tests): fix broken tests - remove `unit.addedBy.instructor.icon_url` because it can be no `Instructor` related to `User`
fix(chat:tests): fix broken tests - remove `unit.addedBy.instructor.icon_url` because it can be no `Instructor` related to `User`

raccoongang/socraticqs2,cjlee112/socraticqs2,cjlee112/socraticqs2,raccoongang/socraticqs2,raccoongang/socraticqs2,cjlee112/socraticqs2,cjlee112/socraticqs2,raccoongang/socraticqs2