Move the database configuration check to Gitlab::Geo

app/models/geo/base_registry.rb

 class Geo::BaseRegistry < ActiveRecord::Base
   self.abstract_class = true
 
-  if Rails.configuration.respond_to?(:geo_database) && (Gitlab::Geo.secondary? || Rails.env.test?)
+  if Gitlab::Geo.configuration_available? && (Gitlab::Geo.secondary? || Rails.env.test?)
     establish_connection Rails.configuration.geo_database
   end
 end

app/workers/geo_backfill_worker.rb

@@ -6,7 +6,7 @@ class GeoBackfillWorker
   BATCH_SIZE = 100.freeze
 
   def perform
-    return unless Rails.configuration.respond_to?(:geo_database)
+    return unless Gitlab::Geo.configuration_available?
     return unless Gitlab::Geo.primary_node.present?
 
     start_time  = Time.now

lib/gitlab/geo.rb

@@ -29,6 +29,10 @@ module Gitlab
       Gitlab::Geo.current_node.reload.enabled?
     end
 
+    def self.configuration_available?
+      Rails.configuration.respond_to?(:geo_database)
+    end
+
     def self.license_allows?
       ::License.current && ::License.current.add_on?('GitLab_Geo')
     end

lib/gitlab/geo/health_check.rb

@@ -3,7 +3,7 @@ module Gitlab
     class HealthCheck
       def self.perform_checks
         return '' unless Gitlab::Geo.secondary?
-        return 'The Geo database configuration file is missing.' unless Rails.configuration.respond_to?(:geo_database)
+        return 'The Geo database configuration file is missing.' unless Gitlab::Geo.configuration_available?
 
         database_version  = self.get_database_version.to_i
         migration_version = self.get_migration_version.to_i