Fix the criteria for an alert silence

.gitlab/issue_templates/failover.md

@@ -155,7 +155,7 @@ an hour before the scheduled maintenance window.
     - `environment`: `prd`
 1. [ ] **PRODUCTION ONLY** 🔪 {+ Chef-Runner +}: Silence production alerts
     * [Create an alert silence](https://alerts.gitlab.com/#/silences/new) for 3 hours (starting now) with the following matchers:
-        * `environment`: `prd`
+        * `provider`: `azure`
         * `alertname`: `High4xxApiRateLimit|High4xxRateLimit`, check "Regex"
 1. [ ] 🔪 {+ Chef-Runner +}: Stop any new GitLab CI jobs from being executed
     * Block `POST /api/v4/jobs/request`