Don't include Paranoia for handling soft-deletions

We're replacing Paranoia with Discard as the only option for
soft-deleting records.

core/app/models/concerns/spree/soft_deletable.rb

@@ -7,12 +7,10 @@ module SoftDeletable
     extend ActiveSupport::Concern
 
     included do
-      acts_as_paranoid
-      include Spree::ParanoiaDeprecations::InstanceMethods
-      extend Spree::ParanoiaDeprecations::ClassMethods
-
       include Discard::Model
       self.discard_column = :deleted_at
+
+      default_scope { kept }
     end
   end
 end

core/spec/models/spree/concerns/soft_deletable_spec.rb

@@ -13,11 +13,6 @@
     end
   end
 
-  it 'includes Paranoia' do
-    expect(Post).to respond_to(:with_deleted)
-    expect(Post.new).to respond_to(:deleted?)
-  end
-
   it 'includes Discard' do
     expect(Post).to respond_to(:with_discarded)
     expect(Post.new).to respond_to(:discarded?)