Removed usage of standard_signin_enabled everywhere

 * This settings is already covered by attribute signin_enabled it's
   a follow-up from foodcritic fixes.

attributes/default.rb

@@ -75,7 +75,6 @@ default['gitlab']['projects_limit'] = 10
 default['gitlab']['user_can_create_group'] = true
 default['gitlab']['user_can_change_username'] = true
 default['gitlab']['default_theme'] = 2
-default['gitlab']['standard_signin_enabled'] = true
 default['gitlab']['repository_downloads_path'] = "tmp/repositories"
 default['gitlab']['oauth_enabled'] = false
 default['gitlab']['oauth_block_auto_created_users'] = true

spec/install_spec.rb

@@ -32,7 +32,6 @@ describe "gitlab::install" do
             user_can_create_group: true,
             user_can_change_username: true,
             default_theme: 2,
-            standard_signin_enabled: true,
             repository_downloads_path: 'tmp/repositories',
             oauth_enabled: false,
             oauth_block_auto_created_users: true,
@@ -467,7 +466,6 @@ describe "gitlab::install" do
             user_can_create_group: true,
             user_can_change_username: true,
             default_theme: 2,
-            standard_signin_enabled: true,
             repository_downloads_path: 'tmp/repositories',
             oauth_enabled: false,
             oauth_block_auto_created_users: true,