remove old workflows

[nullun]

No description provided.

[Copilot]

Pull Request Overview

This PR removes two deprecated GitHub workflow files that are no longer needed in the repository.

• Removes the documentation build trigger workflow that was used to dispatch events to the developer portal
• Removes the build workflow that was used to test MkDocs builds on pull requests

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/update-dev-portal.yml	Removes workflow that triggered documentation builds via repository dispatch
.github/workflows/build.yml	Removes workflow that built and tested MkDocs on pull requests

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