[CI] Unrelated PR comments can cancel in-flight ANSI runs

[felipepessoto]

Bug description

Backend: VL (Velox)
Gluten version: main branch

.github/workflows/velox_backend_ansi.yml listens for every created issue_comment, while its workflow-level concurrency group is stable per PR and has cancel-in-progress: true:

on:
  issue_comment:
    types: [created]

concurrency:
  group: ${{ github.repository }}-ansi-${{ github.event.issue.number || inputs.pr_number }}
  cancel-in-progress: true

The /ansi-test and /ansi-analyze command check is only applied later at jobs.check-comment.if. Workflow-level concurrency is evaluated before that job condition, so any unrelated conversation comment on the same PR can:

1. Start an issue_comment workflow in the same concurrency group.
2. Cancel an in-flight /ansi-test or /ansi-analyze run.
3. Skip check-comment because the new comment is not an ANSI command, leaving no replacement run.

Expected behavior: Only a recognized ANSI command or a manual workflow_dispatch run should cancel an older ANSI run for the same PR.

Actual behavior: Any newly created PR conversation comment can cancel it.

Confirmed reproduction

This was reproduced on PR #12906:

1. At 2026-08-27T05:38:58Z, this comment containing /ansi-test started ANSI run 33043165559.
2. The workflow acknowledged the active run, and build-native-lib started at 05:39:12Z.
3. At 05:39:40Z, an unrelated follow-up comment was posted.
4. Two seconds later it created non-command ANSI run 33043202388 in the same concurrency group.
5. The original run's build-native-lib job was cancelled at 05:39:59Z, while every job in the replacement run was skipped. The original ANSI run therefore disappeared without a replacement.

The same concurrency ordering caused a confirmed eight-shard Delta Spark UT cancellation and is fixed for that workflow by #12906.

Proposed fix

Mirror the command predicate from jobs.check-comment.if in concurrency.cancel-in-progress, as #12906 does for /delta-test, or route non-command comments to a unique concurrency group keyed by github.run_id/github.event.comment.id.

The latter fully isolates unrelated comments, including from the single-pending-run replacement behavior of GitHub Actions concurrency. In either approach, preserve these behaviors:

• A newer /ansi-test or /ansi-analyze command cancels the older ANSI run for that PR.
• workflow_dispatch can replace an older manual run for the same PR.
• Unrelated issue and PR comments neither cancel nor displace real ANSI runs.

Related: #12906

This issue was written with assistance from GitHub Copilot CLI 1.0.80.