fix(ci): skip duplicate merge queue workflows

[gustavovalverde]

Motivation

Mergify queue candidates repeat Docker configuration, deployment-image, and external integration workflows that already ran on the source PRs and are not required queue signals.

Solution

Skip those 3 workflows only for candidates that match the Mergify author, repository, and branch prefix. Required queue checks and fast docs and zizmor checks remain unchanged.

Tests

Workflow syntax, security checks, and the candidate predicate pass. Current Docker failures are fixed by #10967.

Refs #10963

AI Disclosure

OpenAI Codex was used for workflow implementation, testing, and this description.

[Copilot]

Pull request overview

This PR updates Zebra’s GitHub Actions workflows to avoid running expensive “source-only” CI jobs on temporary Mergify merge-queue candidate PRs, reducing redundant runner usage while preserving required merge-queue signals.

Changes:

• Skip the GCP deployment-image workflow’s root set-matrix job when the PR is a Mergify queue candidate (author mergify[bot], same-repo head, mergify/merge-queue/ branch prefix), effectively skipping downstream expensive work for those candidates.
• Skip the integration-test dispatch job for Mergify queue candidates while keeping existing behavior for source PRs, main pushes, and manual runs.
• Skip the Docker validation workflow early for Mergify queue candidates, and prevent the final “alls-green” aggregator job from running when the workflow intentionally skipped at the entrypoint.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
.github/workflows/zfnd-deploy-nodes-gcp.yml	Adds a Mergify-queue-candidate guard to set-matrix to skip downstream deployment-image-related jobs for queue candidates.
.github/workflows/trigger-integration-tests.yml	Adds a guard to avoid dispatching integration tests for Mergify queue candidates while retaining existing fork/manual/main-push rules.
.github/workflows/test-docker.yml	Adds an early guard to skip Docker validation on Mergify queue candidates and ensures the final aggregator job doesn’t run when the workflow is intentionally skipped.

[gustavovalverde]

Superseded by #10971, which now owns the source-only policy and workflow skips for merge queue candidates.