[build] Use self-repository syntax for same-repository references

[arturcic]

Description

• Replace all same-repository action references with the new $/ syntax.
• Replace reusable workflow calls with same-commit $/ references.
• Keep checkout steps that are still required for build scripts, repository files, Docker inputs, or documentation sources.
• Add a narrowly scoped Actionlint workaround for the two diagnostics that do not yet recognize the new syntax.

Related Issue

Resolves #5103

Blocked By

This draft PR is blocked by rhysd/actionlint#711.

Actionlint 1.7.12 does not yet recognize the $/ self-repository syntax. The temporary ignores in .github/actionlint.yaml keep all other lint checks active and should be removed once upstream support is available and used by this repository.

Motivation and Context

Self-repository references resolve actions and reusable workflows from the exact commit running the workflow. This keeps internal composition aligned when callers pin a workflow to a full commit SHA and avoids requiring checkout solely to load an action.

How Has This Been Tested?

• actionlint
• git diff --check
• Verified that .github/workflows contains no remaining workspace-relative uses: ./ references.
• Reviewed every neighboring checkout; each remaining checkout has a separate runtime purpose.

Screenshots

Not applicable.

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[sonarqubecloud]

Quality Gate failed

Failed conditions
C Security Rating on New Code (required ≥ A)

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[Copilot]

Pull request overview

Updates GitHub Actions workflow composition across the repository to use GitHub’s new self-repository $/ syntax for same-repo actions and reusable workflows, ensuring references resolve from the exact commit running the workflow (without requiring checkout solely to load local actions). It also introduces a temporary, narrowly scoped Actionlint ignore configuration to accommodate current Actionlint limitations with the new syntax.

Changes:

• Replaced same-repository reusable workflow calls (previously ./.github/workflows/...) with $/... references in the main CI workflow.
• Replaced same-repository action references (previously ./.github/actions/...) with $/... references across several reusable workflows and docs workflow steps.
• Added .github/actionlint.yaml and updated the Actionlint workflow triggers to include it, to temporarily ignore the two known diagnostics that don’t yet understand $/.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
.github/workflows/docs.yml	Switches cache restore action to $/ syntax in docs build/publish jobs.
.github/workflows/ci.yml	Switches reusable workflow calls and a few internal action steps to $/ syntax.
.github/workflows/actionlint.yml	Ensures Actionlint workflow runs when the Actionlint config file changes.
.github/workflows/_unit_tests.yml	Switches cache restore action to $/ syntax in unit test workflow.
.github/workflows/_publish.yml	Switches cache restore action to $/ syntax in publish workflow.
.github/workflows/_prepare.yml	Switches cache restore action to $/ syntax in prepare workflow.
.github/workflows/_docker.yml	Switches internal cache/docker action references to $/ syntax.
.github/workflows/_docker_manifests.yml	Switches internal cache/docker action references to $/ syntax.
.github/workflows/_build.yml	Switches cache restore action to $/ syntax in build workflow.
.github/workflows/_artifacts_windows.yml	Switches cache restore action to $/ syntax in Windows artifacts workflow.
.github/workflows/_artifacts_linux.yml	Switches internal cache/docker action references to $/ syntax in Linux artifacts workflow.
.github/actionlint.yaml	Adds temporary ignores for the two Actionlint diagnostics that don’t yet support $/.