Fixes potential issue when tags not yet defined.
Fixes potential issue when tags not yet defined.

Issue is on Line 74: new_host_tags = host_tags | chef_roles

If host_tags is still nil at this point, new_host_tags will be set to "true"
DataDog/chef-handler-datadog,DataDog/chef-handler-datadog,cvent/chef-handler-datadog,Shopify/chef-handler-datadog,owen/chef-handler-datadog