feat(ci): govulncheck - add persist-credentials: false to checkout steps

[kakkoyun]

What does this PR do?

Adds persist-credentials: false to all actions/checkout steps in the govulncheck workflows (govulncheck.yml and govulncheck-fix.yml).

Motivation

Per Filippo Valsorda's recommendation, actions/checkout leaves a temporary GitHub token on the runner filesystem by default. Any code executed in the job — including govulncheck downloading the vuln DB, go get fetching modules, and transitive dependency code — can read this token.

Adding persist-credentials: false revokes the token from the filesystem immediately after checkout. The govulncheck-fix.yml workflow still works correctly because its push step uses gh auth setup-git with GH_TOKEN env var, which configures its own credential helper independently of the checkout-persisted credential.

No existing workflow in this repo currently uses persist-credentials: false. This change starts with the govulncheck workflows as a natural follow-up to #4595 — the team can decide whether to adopt it repo-wide.

Technically we should adopt persist-credentials: false across all workflows in this repo. See actions/checkout docs.

Reviewer's Checklist

• N/A — CI/workflow-only change, no Go code modified

References

• Filippo Valsorda: Turn Dependabot Off — section on supply chain attack mitigation
• actions/checkout: persist-credentials — official docs
• PR #4595 — parent govulncheck migration PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.74%. Comparing base (bbfa874) to head (8486c8a).
⚠️ Report is 1 commits behind head on kakkoyun/govulncheck.

Additional details and impacted files

see 18 files with indirect coverage changes

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[pr-commenter]

Benchmarks

Benchmark execution time: 2026-03-26 10:34:08

Comparing candidate commit 31f8814 in PR branch kakkoyun/govulncheck-persist-credentials with baseline commit 169fc65 in branch kakkoyun/govulncheck.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 217 metrics, 7 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

[darccio]

I'm all in to adopt this repo-wide.

[kakkoyun]

I'm all in to adopt this repo-wide.

#4607