Optimize complete plan query

- Pre-fetch the answers, questions, and sections as part of the initial plans query (but only when we are in fact fetching all of the questions and answers).
- This speeds up the mean request time by 25%

Author: momo3404

app/controllers/api/v2/plans_controller.rb

@@ -26,6 +26,7 @@ def index
         raise Pundit::NotAuthorizedError unless @scopes.include?('read')
 
         @plans = PlansPolicy::Scope.new(@resource_owner).resolve
+        @plans = @plans.includes(answers: { question: :section }) if @complete
         @items = paginate_response(results: @plans)
         render '/api/v2/plans/index', status: :ok
       end

app/presenters/api/v2/plan_presenter.rb

@@ -60,7 +60,7 @@ def plan_costs(plan:)
 
       # Fetch all questions and answers from a plan, regardless of theme
       def fetch_all_q_and_a
-        answers = @plan.answers.includes(question: [:section])
+        answers = @plan.answers
         return [] unless answers.present?
 
         answers.filter_map do |answer|