chore: add disk space cleanup steps to CI pipeline (Phase 3)

[vhvb1989]

Summary

Add disk space cleanup steps to the CI pipeline to eliminate 71 "Free disk space on / is lower than 5%" warnings on Linux agents (~62% of all pipeline warnings).

Changes

New file

• eng/pipelines/templates/steps/cleanup-disk-space.yml — Reusable cleanup step template with parameterized targets (Docker, Go cache, NuGet, .NET temp). All steps are Linux-only, use continueOnError: true, and log df -h / before/after for observability.

Modified files

• eng/pipelines/templates/jobs/build-cli.yml — 3 cleanup insertions:
  • After test run → clean NuGet cache and .NET temp artifacts (Go cache preserved for release build)
  • After release build → clean Go build cache
  • After Linux package build → clean Docker images/containers (conditioned on BuildLinuxPackages)
• eng/pipelines/templates/jobs/cross-build-cli.yml — 1 cleanup insertion:
  • After Linux ARM64 package build → clean Docker images + Go cache (conditioned on BuildLinuxPackages)

Design Decisions

• Zero risk: All cleanup steps use continueOnError: true — cleanup failures never break the build
• Linux-only: Conditioned on eq(variables['Agent.OS'], 'Linux') since warnings only affect Linux agents
• Compile-time conditional: ${{ if }} blocks ensure only requested cleanup operations are emitted in each invocation
• Minimal overhead: Each cleanup step completes in seconds
• Preserved Go cache for release build: Post-test cleanup intentionally skips Go cache to avoid rebuilding from scratch for the release binary

Related Issues

Closes #7783
Parent: #4668
Full analysis: Azure/azure-dev-pr#1780

[Copilot]

Pull request overview

This PR adds a reusable Azure Pipelines step template to reclaim disk space on Linux build agents and wires it into the CLI build job templates to reduce “Free disk space on / is lower than 5%” warnings.

Changes:

• Added a reusable cleanup-disk-space.yml step template with parameterized cleanup targets (Docker, Go cache, NuGet, .NET temp) and before/after disk usage logging.
• Inserted cleanup steps into build-cli.yml at multiple points in the job to reduce transient disk pressure.
• Inserted cleanup steps into cross-build-cli.yml after Linux ARM64 package build.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
eng/pipelines/templates/steps/cleanup-disk-space.yml	New reusable cleanup template (Linux-only) for reclaiming disk space via targeted cache/prune steps.
eng/pipelines/templates/jobs/build-cli.yml	Adds multiple invocations of the cleanup template during the BuildCLI job.
eng/pipelines/templates/jobs/cross-build-cli.yml	Adds a cleanup invocation after the Linux ARM64 package build.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

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

[vhvb1989]

/azp run azure-dev - cli

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[github-actions]

📋 Prioritization Note

Thanks for the contribution! The linked issue isn't in the current milestone yet.
Review may take a bit longer — reach out to @rajeshkamal5050 or @kristenwomack if you'd like to discuss prioritization.

[hemarina]

This cleanup template is a good targeted way to reduce Linux agent disk pressure, and the latest iteration addresses the earlier cache-timing and condition feedback. The Linux gating, continueOnError, and before/after df -h / logging make the cleanup behavior observable without making cleanup failures block the build.

I found two follow-up items worth addressing or confirming before merge:

1. eng/pipelines/templates/jobs/build-cli.yml lines 174-178
   The post-test cleanup uses the template default condition of succeeded(). If the test step fails, Publish test results still runs because it uses succeededOrFailed(), but this cleanup step will be skipped. Since reclaiming disk is still useful after failed tests, pass Condition: succeededOrFailed() for this invocation.

2. The affected Azure Pipelines template path does not appear to have been exercised on this PR. The /azp run azure-dev - cli attempt was excluded by pipeline triggers, so the new compile-time ${{ if }} blocks and composed runtime conditions have not been validated in the target ADO pipeline. Please run the affected pipeline to confirm template expansion for the new cleanup wiring.