Set noindex for preview builds of docs site

[encima]

I have read the CONTRIBUTING.md file.

YES

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

Currently, preview builds of the site (i.e. https://docs-rog1zs1kv-supabase.vercel.app) are indexed as X-Robots-Tag is set to all. By default, Vercel sets this to noindex and we override it here

What is the new behavior?

This adds an additional check for the host domain and sets the header to noindex when it is not the production site

Additional context

Fixes #28753

[vercel[bot]]

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Name	Status	Preview	Comments	Updated (UTC)
docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 4, 2024 3:37pm

5 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
design-system	⬜️ Ignored (Inspect)	Visit Preview		Sep 4, 2024 3:37pm
studio	⬜️ Ignored (Inspect)	Visit Preview		Sep 4, 2024 3:37pm
studio-self-hosted	⬜️ Ignored (Inspect)	Visit Preview		Sep 4, 2024 3:37pm
studio-staging	⬜️ Skipped (Inspect)			Sep 4, 2024 3:37pm
zone-www-dot-com	⬜️ Skipped (Inspect)			Sep 4, 2024 3:37pm

[supabase[bot]]

No changes detected in supabase directory. This pull request has been ignored for the connected project xguihxuzqibwxjnimxev due to its connection settings. Go to Project Integrations Settings ↗︎ in order to change this behavior.

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