Update version references in backend_configuration.rb for Solidus 4…

….2.0

The `backend_configuration.rb` file had preferences still pointing to
`Solidus v4.1.0.a`.

This commit updates the references to `Solidus v4.2` to ensure the correct
versioned preferences are loaded.

(cherry picked from commit ff09c3f)

backend/lib/spree/backend_configuration.rb

@@ -16,7 +16,7 @@ class BackendConfiguration < Preferences::Configuration
 
     # @!attribute [rw] theme
     #   @return [String] Default admin theme name
-    versioned_preference :theme, :string, initial_value: 'classic', boundaries: { "4.1.0.a" => "solidus_admin" }
+    versioned_preference :theme, :string, initial_value: 'classic', boundaries: { "4.2.0" => "solidus_admin" }
 
     def theme_path(user_theme = nil)
       user_theme ? themes.fetch(user_theme.to_sym) : themes.fetch(theme.to_sym)
@@ -25,8 +25,7 @@ def theme_path(user_theme = nil)
     # @!attribute [rw] admin_updated_navbar
     #   @return [Boolean] Should the updated navbar be used in admin (default: +false+)
     #
-    # TODO: Update boundaries before merging to `main`
-    versioned_preference :admin_updated_navbar, :boolean, initial_value: false, boundaries: { "4.1.0.a" => true }
+    versioned_preference :admin_updated_navbar, :boolean, initial_value: false, boundaries: { "4.2.0" => true }
 
     preference :frontend_product_path,
       :proc,
@@ -40,7 +39,7 @@ def theme_path(user_theme = nil)
 
     # @!attribute [rw] prefer_menu_item_partials
     #   @return [Boolean] Whether or not to prefer menu item partials when both a partial and children are present.
-    preference :prefer_menu_item_partials, :boolean, default: false
+    versioned_preference :prefer_menu_item_partials, :boolean, initial_value: true, boundaries: { "4.2.0" => false }
 
     autoload :ORDER_TABS, 'spree/backend_configuration/deprecated_tab_constants'
     autoload :PRODUCT_TABS, 'spree/backend_configuration/deprecated_tab_constants'