CelebrateLaunchModal: update CTA copy for free plan sites

[bogiii]

Fixes: DATSCI-1172

Proposed changes

Updates the domain upsell CTA copy in CelebrateLaunchModal for free plan + no custom domain sites: "Claim your domain" → "Get your domain".

The other variants (paid + monthly, paid + annual) are unchanged.

Other information

• Generate changelog entries for this PR (using AI).

Related product discussion/links

• datsci-optimization-site-launch-standardization-b99113373d42

Does this pull request change what data or activity we track or use?

No.

Testing instructions

1. Launch an unlaunched site on a free plan without a custom domain (via the masterbar button, launchpad widget, or Reading Settings)
2. When the CelebrateLaunchModal appears, verify the upsell button reads "Get your domain" instead of "Claim your domain"
3. Verify sites on paid plans or with a custom domain are unaffected

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (WordPress.com Site Helper), and enable the update/celebration-modal-cta-copy-update branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack-mu-wpcom-plugin update/celebration-modal-cta-copy-update

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[github-actions]

Thank you for your PR!

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[jp-launch-control]

Code Coverage Summary

No summary data is available for parent commit 16d37d2, so cannot calculate coverage changes. 😴

If that commit is a feature branch rather than a trunk commit, this is expected. Otherwise, this should be updated once coverage for 16d37d2 is available.

Full summary · PHP report