ci: add concurrency cancellation + job timeouts to data-ingestors CI

[LukasWodka]

Summary

Mechanical CI-hygiene change. Adds a per-ref concurrency group and timeout-minutes to the four non-automation workflows under .github/workflows/:

• e2e.yml — added concurrency only (the e2e job already had timeout-minutes: 15)
• publish-dev.yml — concurrency + timeout-minutes: 20 on publish
• publish-master.yml — concurrency + timeout-minutes: 20 on publish
• release-image.yml — concurrency + timeout-minutes: 30 on release (multi-arch docker build + cosign)

The concurrency group is keyed on github.ref with cancel-in-progress gated to pull_request events only, so push/tag/schedule runs are never cancelled — only superseded PR pushes are. Hung steps now hit the job timeout instead of the 6h runner default.

tests.yml was left untouched (it already has both). No kanban/org-automation caller workflows were modified.

Type: CI hygiene / cost reduction

Test plan

• All four touched workflows parse as valid YAML (yaml.safe_load).
• Concurrency + timeouts only — no change to any job's steps, triggers, or behavior.

🤖 Generated with Claude Code

[LukasWodka]

👋 Heads-up — Code review queue is at 34 / 30

Above the WIP limit. The team convention is to review existing PRs before opening new work.

Open PRs currently in Code review (oldest first):

• .github#57 — fix(fr-gate): pass items at or beyond the required stage · author: @aptracebloc · no reviewer assigned
• .github#60 — feat(security): public-repo PII gate (block customer names + secrets in PRs) · author: @LukasWodka · no reviewer assigned
• averaging-service#117 — refactor(averaging): per-framework weight-handling seam (WS-B B1) · author: @divyasinghds · no reviewer assigned
• averaging-service#118 — feat(averaging): trainable-only keyed-dict weight format (WS-C image_validator falsely rejects images when target_size matches exactly #104) · author: @divyasinghds · no reviewer assigned
• averaging-service#119 — fix(averaging): exact federated GaussianNB merge — usable + correct (WS-B B2, docs: fix staging-recipe link branch ref (main → develop) #112) · author: @divyasinghds · no reviewer assigned
• averaging-service#120 — ci: add concurrency cancellation + job timeouts to averaging-service CI · author: @LukasWodka · no reviewer assigned
• backend#815 — chore(deps): bump cryptography from 47.0.0 to 48.0.1 · author: @dependabot · no reviewer assigned
• backend#829 — feat(#817): failure surfaces a reason end-to-end + stuck-run reaper (WS6 I3/I4/I5/I8) · author: @saadqbal · no reviewer assigned
• cli#78 — fix(dataset rm): delete staging files from a uid-65532 pod, not jobs-manager (Release v0.3.10 (ingestion hardening + path-traversal fix + single-label preflight) #259) · author: @LukasWodka · no reviewer assigned
• cli#79 — chore(schema): re-sync vendored ingest.v1.json from data-ingestors master · author: @LukasWodka · no reviewer assigned

Pull from review before opening new work. (This is a nudge from the kanban WIP check, not a block.)