Don't require a .dbconfig file on any masters.

masters/master.chromium.infra/master.cfg

 # -*- python -*-
 # ex: set syntax=python:
 
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import config
 import master_site_config
 
@@ skipping 31 matching lines @@
     factory_properties=props,
     **kwargs)
 
 revision_getter = master_utils.ConditionalProperty(
     lambda build: build.getProperty('revision'),
     WithProperties('%(revision)s'),
     'origin/master')
 
 ####### DATABASE
 
-config.DatabaseSetup(c, require_dbconfig=ActiveMaster.is_production_host)
+config.DatabaseSetup(c)
 
 ####### CHANGE SOURCES
 
 INFRA_REPO_URL = 'https://chromium.googlesource.com/infra/infra'
 LUCI_GO_REPO_URL = (
     'https://chromium.googlesource.com/external/github.com/luci/luci-go')
 LUCI_GAE_REPO_URL = (
     'https://chromium.googlesource.com/external/github.com/luci/gae')
 RECIPES_PY_REPO_URL = (
     'https://chromium.googlesource.com/external/github.com/luci/recipes-py')
@@ skipping 280 matching lines @@
     relayhost=config.Master.smtp,
     extraRecipients=['swarming-eng@googlegroups.com'],
   ),
 ])
 
 
 ####### PROJECT IDENTITY
 
 c['projectName'] = ActiveMaster.project_name
 c['buildbotURL'] = ActiveMaster.buildbot_url