fix: adding missing spc and itn regions to pdns resolver template

[jtracey93]

This PR replaces #2134 to enable CI/CD checks with required secrets.

Original PR by @joselcaguilar

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This pull request updates the privateDnsResolver.json ARM template to improve region support and clean up the template structure. The most significant change is a comprehensive update to the allowed Azure regions for DNS Private Resolver deployments, ensuring better alignment with current Azure regional availability. Minor formatting and structure improvements have also been made for consistency.

Azure region support:

• Updated the allowedValues list for the region parameter to include a much broader and up-to-date set of Azure regions, removing deprecated or unsupported regions and adding many new ones. This ensures deployments are possible in all currently supported regions.

Template structure and formatting:

• Standardized empty arrays and objects in the dependsOn and variables fields for better readability and consistency (e.g., "dependsOn": [] instead of an empty array with line breaks, and "variables": {} instead of a multi-line empty object). [1] [2] [3]

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Overview/Summary

Private DNS Resolver cannot be deployed using the accelerator through the Portal Experience in Spain Central and Italy North regions, this service is already available on those regions.

This PR fixes/adds/changes/removes

1. Fix the deployment for Private DNS Resolver in Spain Central and Italy North regions

Breaking Changes

N/A

Testing Evidence

Only added more regions to allowedValues array, region availability per product is here

Testing URLs

Azure Public

Azure US Gov (Fairfax)

As part of this Pull Request I have

• Checked for duplicate Pull Requests
• Associated it with relevant issues, for tracking and closure.
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Ensured contribution guidance is followed.
• Updated relevant and associated documentation.
• Updated the "What's New?" wiki page (located: /docs/wiki/whats-new.md)

[jaredfholgate]

LGTM