Fix graphql todo IDs

Also adding specs.

app/presenters/todo_presenter.rb

 # frozen_string_literal: true
 
 class TodoPresenter < Gitlab::View::Presenter::Delegated
-  include GlobalID::Identification
-
   presents :todo
 end

changelogs/unreleased/34850-fix-graphql-todo-ids.yml

+---
+title: Fix Todo IDs in GraphQL API
+merge_request: 19068
+author:
+type: fixed

spec/requests/api/graphql/current_user/todos_query_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Query current user todos' do
+  include GraphqlHelpers
+
+  let_it_be(:current_user) { create(:user) }
+  let_it_be(:commit_todo) { create(:on_commit_todo, user: current_user, project: create(:project, :repository)) }
+  let_it_be(:issue_todo) { create(:todo, user: current_user, target: create(:issue)) }
+  let_it_be(:merge_request_todo) { create(:todo, user: current_user, target: create(:merge_request)) }
+
+  let(:fields) do
+    <<~QUERY
+    nodes {
+      id
+    }
+    QUERY
+  end
+
+  let(:query) do
+    graphql_query_for('currentUser', {}, query_graphql_field('todos', {}, fields))
+  end
+
+  subject { graphql_data.dig('currentUser', 'todos', 'nodes') }
+
+  before do
+    post_graphql(query, current_user: current_user)
+  end
+
+  it 'contains the expected ids' do
+    is_expected.to include(
+      a_hash_including('id' => commit_todo.to_global_id.to_s),
+      a_hash_including('id' => issue_todo.to_global_id.to_s),
+      a_hash_including('id' => merge_request_todo.to_global_id.to_s)
+    )
+  end
+end