Previously we would return an error if duplicate paths were specified.
This could lead to problems in cases where a user has the same path,
say /healthz, on two different ports.
This validation was added to signal a potential misconfiguration.
Instead we will only check for duplicate listener ports, since that is
what would lead to ambiguity issues when generating xDS config.
In the future we could look into using a single listener and creating
distinct filter chains for each path/port.
Freddy