add missing attribute to attr_encrypted so it is fully backwards-compatible

app/models/ci/variable.rb

@@ -13,6 +13,7 @@ module Ci
 
     attr_encrypted :value, 
        mode: :per_attribute_iv_and_salt,
+       insecure_mode: true,
        key: Gitlab::Application.secrets.db_key_base,
        algorithm: 'aes-256-cbc'
   end

app/models/project_import_data.rb

@@ -7,6 +7,7 @@ class ProjectImportData < ActiveRecord::Base
                  marshal: true,
                  encode: true,
                  mode: :per_attribute_iv_and_salt,
+                 insecure_mode: true,
                  algorithm: 'aes-256-cbc'
 
   serialize :data, JSON

app/models/user.rb

@@ -25,6 +25,7 @@ class User < ActiveRecord::Base
   attr_encrypted :otp_secret,
     key:       Gitlab::Application.config.secret_key_base,
     mode:      :per_attribute_iv_and_salt,
+    insecure_mode: true,
     algorithm: 'aes-256-cbc'
 
   devise :two_factor_authenticatable,