Fix unnecessary requirement for deprecated OTP_SECRET environment variable (#34810)

db/post_migrate/20240307180905_migrate_devise_two_factor_secrets.rb

@@ -79,8 +79,18 @@ class MigrateDeviseTwoFactorSecrets < ActiveRecord::Migration[7.1]
   class MigrationUser < ApplicationRecord
     self.table_name = :users
 
+    LEGACY_OTP_SECRET = begin
+      if Rails.env.test?
+        '100c7faeef00caa29242f6b04156742bf76065771fd4117990c4282b8748ff3d99f8fdae97c982ab5bd2e6756a159121377cce4421f4a8ecd2d67bd7749a3fb4'
+      elsif ENV['SECRET_KEY_BASE_DUMMY']
+        SecureRandom.hex(64)
+      else
+        ENV.fetch('OTP_SECRET')
+      end
+    end
+
     devise :two_factor_authenticatable,
-           otp_secret_encryption_key: Rails.configuration.x.otp_secret
+           otp_secret_encryption_key: LEGACY_OTP_SECRET
 
     include LegacyOtpSecret
   end