Add Datadog Synthetic tests workflow

[kerrrang9214-tech]

This workflow triggers Datadog Synthetic tests on push and pull request events to the main branch.

Why:

Closes:

What's being changed (if available, include any code snippets, screenshots, or gifs):

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• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the review environment.

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[github-actions]

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[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions:

• .github/workflows/datadog-synthetics.yml

You'll need to revert all of the files you changed that match that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

The complete list of files we can't accept are:

• .devcontainer/**
• .github/**
• data/reusables/rai/**
• Dockerfile*
• src/**
• package*.json
• content/actions/how-tos/security-for-github-actions/security-hardening-your-deployments/**

We also can't accept contributions to files in the content directory with frontmatter contentType: rai.

[Copilot]

Pull request overview

Adds a new GitHub Actions workflow to run Datadog Synthetic tests when changes are pushed to main or when pull requests target main.

Changes:

• Introduces .github/workflows/datadog-synthetics.yml to run Datadog Synthetics via DataDog/synthetics-ci-github-action.
• Configures triggers for push and pull_request events on the main branch.
• Uses repository secrets (DD_API_KEY, DD_APP_KEY) and a tag-based search query (tag:e2e-tests) to select tests.

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions:

• .github/workflows/datadog-synthetics.yml

You'll need to revert all of the files you changed that match that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

The complete list of files we can't accept are:

• .devcontainer/**
• .github/**
• data/reusables/rai/**
• Dockerfile*
• src/**
• package*.json
• content/actions/how-tos/security-for-github-actions/security-hardening-your-deployments/**

We also can't accept contributions to files in the content directory with frontmatter contentType: rai.