Backport of ci: fix CI skip script hole into release/1.19.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #21741 to be assessed for backporting due to the inclusion of the label backport/1.19.

The below text is copied from the body of the original PR.

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In some environments, the script will not fail despite SKIP_CHECK_BRANCH being unset, leading to the script explicitly skipping CI when it should fail fast.

Meta-comment: we should consider transitioning to paths-ignore. Even though it'd be a bit more copypasta, the upside is we can't silently skip and pass tests + security scans by accident if a future bug or misconfiguration occurs.

Description

Example script failure -> skipped CI: https://github.com/hashicorp/consul/actions/runs/10851790913/job/30116333377#step:3:5 (this workflow no longer uses the script, and relies on paths-ignore instead).

Testing

❯ .github/scripts/check_skip_ci.sh; echo $?
.github/scripts/check_skip_ci.sh: line 16: SKIP_CHECK_BRANCH: SKIP_CHECK_BRANCH is required
1

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

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Overview of commits

• 4ffa6cb

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR