refactor(ci): harmonize sticky PR comment lifecycle

[xnoto]

Summary

Harmonizes the repository’s own CI PR comment lifecycle with the reusable OpenTofu workflow:

• immediately posts/updates an in-progress sticky comment before lint begins;
• preserves the preceding result in a collapsible Previous run output section;
• uses a consistent #### Shared Workflows CI heading plus passed/failed status line;
• removes the old Validation output (redacted, last 12000 characters) caption;
• wraps the captured log in a collapsible View run output section.

The existing marker, permissions, lint command, token redaction, and failure behavior remain unchanged. This is repo-local CI only; no reusable-workflow caller contract changes.

Validation

GitHub Actions CI on this PR is authoritative.

[github-actions]

Shared Workflows CI

Shared workflows CI passed.

View the workflow run.

View run output

[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Initializing environment for https://github.com/gitleaks/gitleaks.
[INFO] Initializing environment for https://github.com/rhysd/actionlint.
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/gitleaks/gitleaks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/rhysd/actionlint.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
check for case conflicts.................................................Passed
check for merge conflicts................................................Passed
check for broken symlinks............................(no files to check)Skipped
check vcs permalinks.....................................................Passed
detect destroyed symlinks................................................Passed
detect private key.......................................................Passed
mixed line ending........................................................Passed
trim trailing whitespace.................................................Passed
Detect hardcoded secrets.................................................Passed
Lint GitHub Actions workflow files.......................................Passed