Avoid ternary operator usage when appending/creating I18n keys

When using the OR operator, if the left side of the expression evaluates
to false, its right side is taken into consideration. Since in Ruby nil
is false, we can avoid using conditionals for this particular scenario

app/controllers/admin/site_customization/information_texts_controller.rb

@@ -66,10 +66,9 @@ class Admin::SiteCustomization::InformationTextsController < Admin::SiteCustomiz
       locale = params[:locale] || I18n.locale
       translations = I18n.backend.send(:translations)[locale.to_sym]
 
-      translations.each do |k, v|
-        @content[k.to_s] = I18nContent.flat_hash(v).keys.map { |s|
-          @existing_keys["#{k.to_s}.#{s}"].nil? ? I18nContent.new(key: "#{k.to_s}.#{s}") :
-                                                  @existing_keys["#{k.to_s}.#{s}"]
+      translations.each do |key, value|
+        @content[key.to_s] = I18nContent.flat_hash(value).keys.map { |string|
+          @existing_keys["#{key.to_s}.#{string}"] || I18nContent.new(key: "#{key.to_s}.#{string}")
         }
       end
     end