Domain connection setup: Show @ for root domains and remove fqdn for subdomains

[gius80]

Part of https://linear.app/a8c/issue/NOMADO-169/update-the-name-texts-on-the-advanced-domain-connection-setup-screen

Proposed Changes

This PR improves the domain connection experience by correcting how DNS records are displayed in the advanced setup for both root domains and subdomains:

• For root domains, A records now display "@" instead of the full domain name.
• For subdomains, A records now display only the subdomain part.
• For subdomains, the CNAME record for www now displays only the subdomain part, prefixed with www.

Why are these changes being made?

These changes enhance the domain connection process by ensuring DNS record formats are accurate for both root domains and subdomains. Most popular domain registrars (including ours) automatically append the domain name when configuring A or CNAME records. As a result, displaying the full domain previously led less technical users to mistakenly create records like domain.ext.domain.ext, causing connection issues and user frustration.

Domains
BEFORE	AFTER

Subdomains
BEFORE	AFTER

Testing Instructions

This PR depends on this backend update: 183202-ghe-Automattic/wpcom

• Connect a new domain, then follow the advance setup and verify that the A records name show @ instead of the domain name.
• Now test a subdomain connection. The A name records should show the subdomain part and the CNAME should show www + subdomain part.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-144938

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-144938&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-144938&env=a8c-for-agencies

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~69 bytes added 📈 [gzipped])

name                        parsed_size           gzip_size
domains                          +114 B  (+0.0%)      +69 B  (+0.0%)
async-step-use-my-domain         +114 B  (+0.0%)      +69 B  (+0.0%)
async-step-unified-domains       +114 B  (+0.0%)      +69 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Async-loaded Components (~69 bytes added 📈 [gzipped])

name                             parsed_size           gzip_size
async-load-signup-steps-domains       +114 B  (+0.0%)      +69 B  (+0.0%)

React components that are loaded lazily, when a certain part of UI is displayed for the first time.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[leonardost]

Tested with the corresponding WPCOM PR and LGTM! Thanks for this update!

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• blaze-dashboard
• command-palette-wp-admin
• help-center
• notifications
• odyssey-stats
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug update/connect-domain-advance-setup-records on your sandbox.