Adding ADO service principal (#6647)

## What are you changing in this pull request and why?

This PR adds the ADO service principal configuration instructions

## Checklist
- [ ] I have reviewed the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
so my content adheres to these guidelines.
- [ ] The topic I'm writing about is for specific dbt version(s) and I
have versioned it according to the [version a whole
page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
and/or [version a block of
content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content)
guidelines.
- [ ] I have added checklist item(s) to this list for anything anything
that needs to happen before this PR is merged, such as "needs technical
review" or "change base branch."
- [ ] The content in this PR requires a dbt release note, so I added one
to the [release notes
page](https://docs.getdbt.com/docs/dbt-versions/dbt-cloud-release-notes).
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<!-- vercel-deployment-preview -->
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🚀 Deployment available! Here are the direct links to the updated files:


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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/build/enhance-your-code
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/build/incremental-strategy
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/cloud/about-cloud-develop-defer
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/cloud/git/setup-azure
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/connect-adapters
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/dbt-cloud-apis/sl-api-overview
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/dbt-cloud-apis/user-tokens
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/deploy/monitor-jobs
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/docs/supported-data-platforms
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https://docs-getdbt-com-git-service-principal-dbt-labs.vercel.app/reference/resource-configs/hard-deletes

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