remove UserStub related code

GitOrigin-RevId: df2559395d1c7f386a07feb5a2ff3c07b6922350

services/web/app/src/infrastructure/mongojs.js

@@ -8,7 +8,6 @@ const mongojs = require('mongojs')
 const db = mongojs(Settings.mongo.url, [
   'projects',
   'users',
-  'userstubs',
   'tokens',
   'docSnapshots',
   'projectHistoryFailures'

services/web/app/src/models/UserStub.js

@@ -1,14 +0,0 @@
-const mongoose = require('../infrastructure/Mongoose')
-const { Schema } = mongoose
-
-const UserStubSchema = new Schema({
-  email: { type: String, default: '' },
-  first_name: { type: String, default: '' },
-  last_name: { type: String, default: '' },
-  overleaf: { id: { type: Number } },
-  thirdPartyIdentifiers: { type: Array, default: [] },
-  confirmed_at: Date
-})
-
-exports.UserStub = mongoose.model('UserStub', UserStubSchema)
-exports.UserStubSchema = UserStubSchema