Add size-based HAProxy log rotation with hourly checks

[Copilot]

What this PR does

• Rotation policy: Add maxsize 1G while preserving daily rotation, seven retained logs, compression, and the rsyslog reopen hook.
• Scheduling: Apply an hourly logrotate timer override on install and upgrade, with one-minute accuracy.
• Ownership: Keep rotation configuration root-owned; preserve existing ownership defaults for other rendered files.
• Coverage: Add policy, ownership, and upgrade tests; update the changelog and exclude generated virtualenv symlinks.

Why we need it

High-traffic ingresses can exhaust disk space before time-based rotation runs, causing unit errors and service disruption. Size-triggered rotation with hourly checks reduces that risk without adding charm configuration options.

Checklist

• I followed the contributing guide
• I added or updated the documentation (if applicable)
• I updated docs/changelog.md with user-relevant changes
• I added a change artifact for user-relevant changes in docs/release-notes/artifacts. If no change artifact is necessary, I tagged the PR with the label no-release-note.
• I used AI to assist with preparing this PR
• I added or updated tests as needed (unit and integration)
• If integration test modules are used: I updated the workflow configuration
  (e.g., in .github/workflows/integration_tests.yaml, ensure the modules list is correct)
• If this PR involves a Grafana dashboard: I added a screenshot of the dashboard
• If this PR involves Terraform: terraform fmt passes and tflint reports no errors

Test plan

354 unit tests passed. Isolated logrotate checks covered repeated same-day size rotation, daily behavior, compression, and retention. Lint, Bandit, CodeQL, and secret scans passed.

Review focus

• The timer override checks all system logrotate policies hourly; their individual rotation rules remain unchanged.
• 1G is a rotation threshold, not a hard cap: logs can grow beyond it between checks.
• No new dependencies, public charm APIs, or workflow changes. Existing deployments receive the new policy on upgrade.

• Fixes [Bug]: Lack of logrotate configuration causes disk exhaustion and unit crashes for high-traffic ingresses #638

[Thanhphan1147]

[merge bot]: This PR is now being monitored to automatically rerun failing tests

[Thanhphan1147]

@copilot add logrotate to .custom_wordlist

[Copilot]

@copilot add logrotate to .custom_wordlist

Added logrotate to docs/.custom_wordlist.txt in commit 0fb91e3. The documentation spelling check passes across all 39 files.