Condense progress output for seeding burndown

ee/db/fixtures/development/20_burndown.rb

@@ -12,16 +12,16 @@ class Gitlab::Seeder::Burndown
     Sidekiq::Worker.skipping_transaction_check do
       Sidekiq::Testing.inline! do
         create_milestone
-        puts '.'
+        print '.'
 
         create_issues
-        puts '.'
+        print '.'
 
         close_issues
-        puts '.'
+        print '.'
 
         reopen_issues
-        puts '.'
+        print '.'
       end
     end