[agents] Mandate concise reports in security triaging skills

Tighten Phase 5, Phase 6, and the Technical Quality Checklist in
v8-security-triaging and v8-poc-classification to produce compact,
high-signal Buganizer triage comments:
- Limit metadata fields to a single line and Rationale to 2-4 sentences.
- Require concise single-line sub-bullets in 'Local Reproduction
  Findings' (allowing multi-line GDB backtraces when helpful, and not
  requiring a Gerrit link for the Build commit).
- Forbid local workstation paths in Buganizer comment text.
- Update the Phase 6 Auditor and checklist to enforce brevity and verify
  against the Orchestrator's INVOKER_INFO_SESSION_ID.
- Fix version header references to point to include/v8-version.h.

TAG=agy
R=ishell@chromium.org

Change-Id: I65a814debd5b3da7ae3c0cc89a19a3377efcfa26
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/8479632
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#110180}