Set the health_check mailer full checks to be the same as the standard checks

There was nothing additional in the full checks that we want to run (email, custom)

config/initializers/health_check.rb

@@ -13,4 +13,5 @@ end
 HealthCheck.setup do |config|
   config.standard_checks = ['database', 'migrations', 'cache']
+  config.full_checks = ['database', 'migrations', 'cache']
 end