Backport of enforce validation for missing service name in registration into release/1.21.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #22381 to be assessed for backporting due to the inclusion of the label backport/1.21.

🚨

Warning automatic cherry-pick of commits failed. If the first commit failed,
you will see a blank no-op commit below. If at least one commit succeeded, you
will see the cherry-picked commits up to, not including, the commit where
the merge conflict occurred.

The person who merged in the original PR is:
@sreeram77
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: unable to process merge commit: "bc526e57ec0ba48818e279e235512a4380570379", automatic backport requires rebase workflow

The below text is copied from the body of the original PR.

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Description

Adds validation to the catalog register endpoint to ensure that a service name (Service.Service) is provided when registering a service. This prevents registrations with empty service names, which resulted in the Services page in the Consul UI being broken.

If both Service.ID and Service.Service are empty, the API now returns an error message.

Testing & Reproduction steps

• Added unit test TestCatalog_Register_RejectsMissingServiceName in catalog_endpoint_test.go
• Manually validated behavior using:

curl -X PUT http://localhost:8500/v1/catalog/register \
  -H "Content-Type: application/json" \
  --data-raw '{
    "Datacenter": "dc1",
    "Node": "my_node",
    "Address": "123.456.78.9",
    "Service": {
      "ID": "",
      "Service": "",
      "Port": 9001
    }
  }'

service name (Service.Service) is required; both Service ID (Service.ID) and Service Name cannot be empty

Links

PR Checklist

• [x ] updated test coverage
• external facing docs updated
• appropriate backport labels added
• [x ] not a security concern

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Overview of commits

• b905c26 - 142b9d6 - 6a027bf - bc526e5

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR

[markcampv]

LGTM