Fix all Rails/FilePath rubocop issues

.rubocop_todo.yml

@@ -365,12 +365,6 @@ Performance/RedundantMatch:
     - 'app/controllers/valuation/spending_proposals_controller.rb'
     - 'app/helpers/embed_videos_helper.rb'
 
-# Offense count: 2
-Rails/FilePath:
-  Exclude:
-    - 'app/controllers/sandbox_controller.rb'
-    - 'spec/spec_helper.rb'
-
 # Offense count: 16
 # Cop supports --auto-correct.
 # Configuration parameters: Include.

app/controllers/sandbox_controller.rb

@@ -6,7 +6,7 @@ class SandboxController < ApplicationController
   helper_method(:namespace)
 
   def index
-    @templates = Dir.glob(Rails.root.join('app/views/sandbox/*.html.erb').to_s).map do |filename|
+    @templates = Dir.glob(Rails.root.join('app', 'views', 'sandbox', '*.html.erb').to_s).map do |filename|
       filename = File.basename(filename, File.extname(filename))
       filename unless filename.starts_with?('_') || filename == 'index.html'
     end.compact

spec/spec_helper.rb

@@ -39,7 +39,7 @@ RSpec.configure do |config|
   config.before(:each) do |example|
     DatabaseCleaner.strategy = :transaction
     I18n.locale = :en
-    load "#{Rails.root}/db/seeds.rb"
+    load Rails.root.join('db', 'seeds.rb').to_s
   end
 
   config.before(:each, type: :feature) do