Alerting: Integration tests for Receiver API (#90632)

---------

Co-authored-by: Matthew Jacobson <matthew.jacobson@grafana.com>

pkg/tests/apis/alerting/notifications/receivers/test-data/notification-settings.json

@@ -0,0 +1,45 @@
+{
+  "template_files": {},
+  "template_file_provenances": {},
+  "alertmanager_config": {
+    "route": {
+      "receiver": "grafana-default-email",
+      "routes": [
+        {
+          "receiver": "user-defined",
+          "object_matchers": [
+            [
+              "test",
+              "=",
+              "test"
+            ]
+          ]
+        }
+      ]
+    },
+    "receivers": [
+      {
+        "name": "grafana-default-email",
+        "grafana_managed_receiver_configs": [
+          {
+            "type": "email",
+            "settings": {
+              "addresses": "example@email.com"
+            }
+          }
+        ]
+      },
+      {
+        "name": "user-defined",
+        "grafana_managed_receiver_configs": [
+          {
+            "type": "email",
+            "settings": {
+              "addresses": "example@email.com"
+            }
+          }
+        ]
+      }
+    ]
+  }
+}

pkg/tests/apis/alerting/notifications/receivers/test-data/rulegroup-1.json

@@ -0,0 +1,34 @@
+{
+  "name": "Group1",
+  "interval": "1m",
+  "rules": [
+    {
+      "for": "0",
+      "labels": {
+        "label1": "test-label"
+      },
+      "annotations": {
+        "annotation": "test-annotation"
+      },
+      "grafana_alert": {
+        "title": "Rule1",
+        "condition": "A",
+        "data": [
+          {
+            "refId": "A",
+            "datasourceUid": "__expr__",
+            "model": {
+              "expression": "0 > 0",
+              "type": "math"
+            }
+          }
+        ],
+        "no_data_state": "NoData",
+        "exec_err_state": "Alerting",
+        "notification_settings": {
+          "receiver": "user-defined"
+        }
+      }
+    }
+  ]
+}