Remove check for "migrated-ness"

[leggsimon]

I don't think we really have a concept of "migrated users" anymore since every syndication should be migrated now. Any references to it (such as below) and newly obsolete/unused code should be removed.

n-syndication/src/js/index.js

Line 88 in 0836f73

if (user && user.migrated === true) {