core(canonical): remove cross-origin check

[whitep4nth3r]

Summary

This PR removes the warning regarding canonical URLs being on a different domain, as discussed in #12572.

This warning predates advice given before 2009 and is now no longer relevant.

Related Documentation

The related documentation listed below is collected from the issue linked above:

• https://www.bing.com/webmasters/help/webmaster-guidelines-30fba23a
• https://uk.help.yahoo.com/kb/SLN2213.html
• https://yoast.com/rel-canonical/#:~:text=the%20canonical%20link%20element%20was%20introduced%20by%20google%2C%20bing%2C%20and%20yahoo!%20in%20february%202009
• https://www.mattcutts.com/blog/canonical-link-tag/

Related Issues/PRs

Related issue: #12572.

[connorjclark]

Thanks! You'll need to run yarn update:sample-json to update some files, since a i18n string was removed.

[connorjclark]

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[connorjclark]

I assume you're in the UK–sorry for the late night requests! I hope to do a Lighthouse release today and having this PR would be great

[whitep4nth3r]

@googlebot I signed it!

[whitep4nth3r]

No worries @connorjclark – I'm excited to finally get rid of this warning! 😀