agent/config will turn [{}] into {} (single element maps into a single
map) to work around HCL issues. These are resolved in HCL2 which I'm
sure Consul will switch to eventually.
This breaks the connect proxy configuration in service definition FILES
since we call this patch function. For now, let's just special-case skip
this. In the future we maybe Consul will adopt HCL2 and fix it, or we
can do something else if we want. This works and is tested.