Skip PR checks for events triggered by Dependabot

[mbg]

Skips the PR checks for workflow runs triggered by Dependabot. We always add the Rebuild label to Dependabot PRs, which triggers a separate workflow to rebuild JS files or workflow templates. As of #3128, the concurrency settings mean that the workflows initiated by Dependabot will be cancelled once the Rebuild job has pushed changes. This PR modifies the PR checks so that they don't run to begin with.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Pull Request Overview

This PR modifies the PR check workflows to skip execution when the triggering actor is Dependabot. The purpose is to prevent redundant workflow runs since Dependabot PRs trigger separate rebuild workflows that cancel the initial runs due to concurrency settings.

• Adds conditional execution logic to skip workflows for Dependabot-triggered events
• Updates the Python script that generates workflow files to include the Dependabot check
• Applies the same conditional check across all generated workflow files

Reviewed Changes

Copilot reviewed 56 out of 56 changed files in this pull request and generated no comments.

File	Description
pr-checks/sync.py	Adds Dependabot check to the workflow generation template
.github/workflows/__*.yml	All generated workflow files updated with Dependabot skip condition

[henrymercer]

Non-generated workflows too?