Migrate lightweight workflows to ubuntu-slim runners

[Copilot]

What is being addressed

GitHub's ubuntu-slim runners (1 vCPU, 5GB RAM, 15min timeout, container-based) offer faster startup and lower costs. Current workflows uniformly use ubuntu-latest regardless of actual resource needs or Docker requirements.

How is this addressed

Migrated 4 workflows to ubuntu-slim:

• flag_external_pr.yml - PR author verification
• pr_comment_bot.yml - comment parsing job only (not destroy jobs - may exceed timeout)
• build_docs.yml - mkdocs build/deploy
• deploy_tre_branch.yml - hash computation

Selection criteria: <5min execution, JavaScript actions only, no Docker dependencies.

Not migrated due to Docker container action incompatibilities:

• test_results.yml - uses EnricoMi/publish-unit-test-result-action@v2 (Docker)
• build_docker_images.yml - uses docker/build-push-action
• build_validation_develop.yml - uses super-linter (Docker)
• cli-package.yml - uses devcontainer (Docker)

Not migrated due to timeout constraints:

• clean_validation_envs.yml - 30min timeout exceeds ubuntu-slim 15min limit
• pr_comment_bot.yml destroy jobs - Azure RG deletion timing

Action type verification:

• JavaScript actions (compatible): actions/checkout, actions/setup-python, actions/github-script, azure/login, LouisBrunner/checks-action
• Docker actions (incompatible): EnricoMi/publish-unit-test-result-action@v2

Updated CHANGELOG.md with PR reference (#4831).

Original prompt

Github has recently released to GA a smaller hosted agents called "ubuntu-slim". We need to review the workflows in this repo and identify small, short running workflows that could benefit from this new type of more efficient hosted agent.

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[github-actions]

Unit Test Results

0 tests   0 ✅  0s ⏱️
0 suites  0 💤
0 files    0 ❌

Results for commit e2f22a0.

♻️ This comment has been updated with latest results.

[Copilot]

Pull request overview

This PR migrates lightweight GitHub Actions workflows to ubuntu-slim runners (1 vCPU, 5GB RAM, 15min timeout) for improved startup performance and reduced costs. The changes target short-running workflows that use only JavaScript actions and have no Docker dependencies.

Changes:

• Migrated 4 workflows/jobs to ubuntu-slim runners: PR author verification, comment parsing, documentation deployment, and branch deployment preparation
• Updated CHANGELOG.md to document the migration

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/pr_comment_bot.yml	Migrates comment parsing job to ubuntu-slim (destroy jobs intentionally kept on ubuntu-latest due to timeout constraints)
.github/workflows/flag_external_pr.yml	Migrates PR author verification job to ubuntu-slim
.github/workflows/deploy_tre_branch.yml	Migrates branch preparation/hash computation job to ubuntu-slim
.github/workflows/build_docs.yml	Migrates documentation build and deployment to ubuntu-slim
CHANGELOG.md	Documents the workflow migration under ENHANCEMENTS section

[tamirkamara]

/test-force-approve

[github-actions]

🤖 pr-bot 🤖

✅ Marking tests as complete (for commit 90a9f11)

(in response to this comment from @tamirkamara)

[JC-wk]

LGTM

[tamirkamara]

/test-force-approve

[github-actions]

🤖 pr-bot 🤖

✅ Marking tests as complete (for commit e2f22a0)

(in response to this comment from @tamirkamara)