Migrate lightweight workflows to ubuntu-slim runners (#4831)

* Initial plan

* Migrate GitHub Actions workflows to ubuntu-slim runners

Co-authored-by: tamirkamara <26870601+tamirkamara@users.noreply.github.com>

* Revert ubuntu-slim for workflows requiring Docker or long execution times

Co-authored-by: tamirkamara <26870601+tamirkamara@users.noreply.github.com>

* Revert test_results.yml to ubuntu-latest due to Docker action dependency

Co-authored-by: tamirkamara <26870601+tamirkamara@users.noreply.github.com>

* Add PR reference to CHANGELOG entry for ubuntu-slim migration

Co-authored-by: tamirkamara <26870601+tamirkamara@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: tamirkamara <26870601+tamirkamara@users.noreply.github.com>

Author: Copilot

.github/workflows/build_docs.yml

@@ -15,7 +15,7 @@ permissions:
 jobs:
   deploy:
     name: Deploy Documentation
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     permissions:
       contents: write
     steps:

.github/workflows/deploy_tre_branch.yml

@@ -35,7 +35,7 @@ permissions:
 jobs:
   prepare-not-main:
     name: Preparation
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     if: |
       github.ref != 'refs/heads/main'
     outputs:

.github/workflows/flag_external_pr.yml

@@ -12,7 +12,7 @@ permissions:
 jobs:
   check_author:
     name: Check PR author
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     permissions:
       contents: read
       pull-requests: write

.github/workflows/pr_comment_bot.yml

@@ -20,7 +20,7 @@ jobs:
     # - the comment is on a PR
     # - the commenting user has write permissions (i.e. is OWNER or COLLABORATOR)
     if: ${{ github.event.issue.pull_request }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     permissions:
       pull-requests: write
       checks: write

CHANGELOG.md

@@ -17,6 +17,7 @@ ENHANCEMENTS:
 * Update `api_healthcheck.sh` script with fixed 10-second check intervals and 7-minute timeout for improved API health monitoring ([#4807](https://github.com/microsoft/AzureTRE/issues/4807))
 * Update SuperLinter to version 8.3.2 ([#4815](https://github.com/microsoft/AzureTRE/issues/4815))
 * Add porter build cache in CI ([#4827](https://github.com/microsoft/AzureTRE/issues/4827))
+* Migrate GitHub Actions workflows to use ubuntu-slim runners for improved efficiency and reduced cost ([#4831](https://github.com/microsoft/AzureTRE/pull/4831))
 
 BUG FIXES:
 * Replace deprecated `--username` flag with `--client-id` in `az login --identity` commands across all Porter bundles ([#4817](https://github.com/microsoft/AzureTRE/issues/4817))