Terminating Gateway only populates service instance from the first external node when Node address is a DNS name

Overview of the Issue

When multiple instances of external services are registered with node.address as the DNS name, only the service instance from the first node gets populated in the terminating gateway clusters.

Reproduction Steps

Steps to reproduce this issue, eg:

Run a consul dev cluster
```
$ consul agent -dev
```

Create a terminating gateway config entry

# file: tg.hcl
Kind = "terminating-gateway"
Name = "legacy-services-gateway"
Services = [
 {
   Name = "counting"
 }
]

$ consul config write tg.hcl

Start the terminating gateway

$ consul connect envoy -gateway=terminating -service legacy-services-gateway -register

Register two external services. We will use the node names as b and c initially to show that only instances from node b are registered.

i. register service with node name b

# file: b.external.json

{
  "Node": "b",
  "Address": "google.com",
  "NodeMeta": {
    "external-node": "true",
    "external-probe": "true"
  },
  "Service": {
    "ID": "counting1",
    "Service": "counting",
    "Port": 9003
  }
}

$ curl -X PUT --data @b.external.json localhost:8500/v1/catalog/register
true

$ curl -s localhost:19000/clusters | grep hostname
counting.default.dc1.internal.4b90cae1-8761-7e60-1dce-fabbe4082006.consul::142.250.70.142:9003::hostname::google.com
local_agent::127.0.0.1:8503::hostname::

ii. register service with node name c

# file: c.external.json

{
  "Node": "c",
  "Address": "wikipedia.org",
  "NodeMeta": {
    "external-node": "true",
    "external-probe": "true"
  },
  "Service": {
    "ID": "counting2",
    "Service": "counting",
    "Port": 9003
  }
}

$ curl -X PUT --data @c.external.json localhost:8500/v1/catalog/register
true

$ curl -s localhost:19000/clusters | grep hostname
counting.default.dc1.internal.4b90cae1-8761-7e60-1dce-fabbe4082006.consul::142.250.70.142:9003::hostname::google.com
local_agent::127.0.0.1:8503::hostname::

You will find that the service registered with node name c doesn't appear in the clusters list.

# file: a.external.json

{
  "Node": "a",
  "Address": "hashicorp.com",
  "NodeMeta": {
    "external-node": "true",
    "external-probe": "true"
  },
  "Service": {
    "ID": "counting3",
    "Service": "counting",
    "Port": 9003
  }
}

$ curl -X PUT --data @a.external.json localhost:8500/v1/catalog/register
true

$ curl -s localhost:19000/clusters | grep hostname
local_agent::127.0.0.1:8503::hostname::
counting.default.dc1.internal.5e540109-8fa5-2940-b277-3a717568c2e5.consul::76.76.21.21:9003::hostname::hashicorp.com

Notice how the cluster changed to hashicorp.com with node name a.

This works perfectly when the external nodes are registered with IP Addresses.

Example clusters when using IP Addresses for node.Address

$ curl -s localhost:19000/clusters | grep hostname
local_agent::127.0.0.1:8503::hostname::
counting.default.dc1.internal.8da69c37-1cbc-ddef-2819-7f22d0163d9f.consul::1.1.1.1:9003::hostname::
counting.default.dc1.internal.8da69c37-1cbc-ddef-2819-7f22d0163d9f.consul::2.2.2.2:9003::hostname::
counting.default.dc1.internal.8da69c37-1cbc-ddef-2819-7f22d0163d9f.consul::3.3.3.3:9003::hostname::

Consul info for both Client and Server

Client info

``` agent: check_monitors = 0 check_ttls = 0 checks = 1 services = 1 build: prerelease = revision = bd257019 version = 1.14.3 version_metadata = consul: acl = disabled bootstrap = false known_datacenters = 1 leader = true leader_addr = 127.0.0.1:8300 server = true raft: applied_index = 277 commit_index = 277 fsm_pending = 0 last_contact = 0 last_log_index = 277 last_log_term = 2 last_snapshot_index = 0 last_snapshot_term = 0 latest_configuration = [{Suffrage:Voter ID:e7c2fe1e-0c1d-e1ad-169d-b1a46432eec2 Address:127.0.0.1:8300}] latest_configuration_index = 0 num_peers = 0 protocol_version = 3 protocol_version_max = 3 protocol_version_min = 0 snapshot_version_max = 1 snapshot_version_min = 0 state = Leader term = 2 runtime: arch = amd64 cpu_count = 8 goroutines = 157 max_procs = 8 os = darwin version = go1.19.4 serf_lan: coordinate_resets = 0 encrypted = false event_queue = 1 event_time = 2 failed = 0 health_score = 0 intent_queue = 0 left = 0 member_time = 1 members = 1 query_queue = 0 query_time = 1 serf_wan: coordinate_resets = 0 encrypted = false event_queue = 0 event_time = 1 failed = 0 health_score = 0 intent_queue = 0 left = 0 member_time = 1 members = 1 query_queue = 0 query_time = 1 ```

Server info

Operating system and Environment details

OS, Architecture, and any other information you can provide about the environment.

Log Fragments

Include appropriate Client or Server log fragments. If the log is longer than a few dozen lines, please include the URL to the gist of the log instead of posting it in the issue. Use -log-level=TRACE on the client and server to capture the maximum log detail.

hashicorp / consul