Modify the Alternate URL generation logic

The logic used to generate alternate URLs (used for hreflang SEO tags and language selectors) has been updated to apply a strict priority sequence when resolving the host for each language: Custom Canonical URL first, then Localized Virtual Host, then Default Virtual Host. Previously, localized virtual host configurations were not factored in, causing alternate URLs to use the default virtual host even when a language-specific one was configured. Sites with localized virtual host configurations will now generate different alternate URLs than before this change. Teams should validate their sitemap and hreflang outputs after updating to confirm the new URLs reflect the intended domain-per-language setup.