Remove username column (#5052)

server/test/factories.ts

@@ -182,7 +182,6 @@ export async function buildUser(overrides: Partial<User> = {}) {
     {
       email: `user${count}@example.com`,
       name: `User ${count}`,
-      username: `user${count}`,
       createdAt: new Date("2018-01-01T00:00:00.000Z"),
       updatedAt: new Date("2018-01-02T00:00:00.000Z"),
       lastActiveAt: new Date("2018-01-03T00:00:00.000Z"),

server/test/support.ts

@@ -28,7 +28,6 @@ export const seed = async () => {
     const admin = await User.create(
       {
         email: "admin@example.com",
-        username: "admin",
         name: "Admin User",
         teamId: team.id,
         isAdmin: true,