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

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#### 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:

1. Run a consul dev cluster
```
$ consul agent -dev
```
2. Create a terminating gateway config entry

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

```
$ consul config write tg.hcl
```

3. Start the terminating gateway

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

4. 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.

5. Register a new service with node name `a`

```
# 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

```
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

```

### 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](https://gist.github.com/) 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.

Reproduce the behavior with the terminating gateway, tg.hcl, and the b.external.json, c.external.json, and a.external.json registrations, then inspect the gateway's handling of external nodes with DNS addresses. Confirm the resulting clusters output includes every registered service instance, while the IP-address case remains correct.

Written by the indexing model from the issue text.