Reduce the number of locales for milestones seeds

Creating records for every locale was taking too long now that CONSUL is
available in 15 languages.

db/dev_seeds.rb

@@ -15,6 +15,10 @@ def log(msg)
   @logger.info "#{msg}\n"
 end
 
+def random_locales
+  [I18n.default_locale, *I18n.available_locales.sample(4)].uniq
+end
+
 require_relative 'dev_seeds/settings'
 require_relative 'dev_seeds/geozones'
 require_relative 'dev_seeds/users'

db/dev_seeds/milestones.rb

@@ -14,7 +14,7 @@ section "Creating investment milestones" do
           status_id: Milestone::Status.all.sample
         )
 
-        I18n.available_locales.map do |locale|
+        random_locales.map do |locale|
           Globalize.with_locale(locale) do
             milestone.description = "Description for locale #{locale}"
             milestone.title = I18n.l(Time.current, format: :datetime)