feat: add test alert group with low thresholds for notification testing

environments/dev/adibrov/alerts/test/test_cpu_firing.yaml

@@ -0,0 +1,21 @@
+name: "DEV ADIBROV - TEST CPU > 2%"
+expression: |
+  (
+    1 - avg by(instance) (rate(node_cpu_seconds_total{job="node_exporter", mode="idle"}[1m]))
+  ) * 100
+threshold: 2
+for: "1m"
+condition_type: "gt"
+need_reduce: true
+reducer_type: "max"
+no_data_state: "OK"
+exec_err_state: "OK"
+labels:
+  service: "test"
+  severity: "info"
+  status: "test"
+  team: "infra"
+summary: |
+  [TEST] CPU {{ printf "%.1f" $values.B.Value }}% на {{ $labels.instance }}
+description: |
+  Тестовый алерт — срабатывает при CPU > 2%. Используется для проверки доставки уведомлений.