ci: update slo check and slo notification rules

[igoragoli]

What does this PR do?

• Adds workflow: auto_cancel: on_new_commit: interruptible: true to .gitlab-ci.yml to always cancel jobs with interruptible: true on new commits. ¹
• Make notify-slo-breaches always run, regardless of the success or failure of check-slo-breaches to make sure we get warning notifications.

Less importantly:

• Simplify macrobenchmarks and pre-release gates rules and adds YAML anchors for readability and DRYness.
• Clean up comments on macrobenchmarks.yml, add explanatory comments when needed, fix pre-release gates comment.

Motivation

https://datadoghq.atlassian.net/browse/APMSP-2373

In summary:

• Previous interruptible policies were incomplete.
• notify-slo-breaches must run even when check-slo-breaches succeeds (for notifying for warnings).

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• New code is free of linting errors. You can check this by running ./scripts/lint.sh locally.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

Unsure? Have a question? Request a review!

Footnotes

1. The default behavior, conservative, is insufficient. It cancels the pipeline if no jobs with interruptible: false (the default) have started. If there is a job before benchmarks with interruptible: false that has started, e.g., wait_for_github_workflow, GitLab won't interrupt those benchmarks. See https://docs.gitlab.com/ci/yaml/#workflowauto_cancelon_new_commit ↩

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-11-27 07:28:40

Comparing candidate commit 033aac9 in PR branch augusto/apmsp-2373.update-slo-check with baseline commit 6503799 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 16 metrics, 8 unstable metrics.

[datadog-official]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

_{This comment will be updated automatically if new data arrives.
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[igoragoli]

Converted to draft since I still would like to test if rules are propagated to child pipelines.