[codex] Remove stale Cloud Run pusher references

[Git-on-my-level]

Summary

• remove the dead commented Cloud Run deploy block from the pusher workflow
• remove pusher from Cloud Run error panels in the backend monitoring dashboard

Why

Pusher is deployed and monitored through GKE today. The stale Cloud Run pusher service in dev has a broken latest revision and is not the authoritative deploy path, so keeping it in Cloud Run deploy/monitoring surfaces creates false operational noise.

Validation

• python3 -m json.tool backend/charts/monitoring/dashboards/general/backend-api-monitoring-v2.json
• git diff --check

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Re-trigger cubic}