Alerting: Fix changing datasource and creating new query not using defaults. (#63092)

* Set default query when changing data source or adding new alert query

* Set default query when creating new alert rule

* Set fefault query for cloud and recording rules

* Create hook for getting defaults in AlertRuleForm

* fixing tests

* Use conditionals with 'if' for more clarity and rename lazy to async

* Add loading indicator for default queries

* Fix tests

* Make newModel a sync method and fix tests error

* Use useAsync instead of useEffect for an async call

packages/grafana-runtime/src/services/__mocks__/dataSourceSrv.ts

@@ -19,5 +19,12 @@ export function getDataSourceSrv() {
   return {
     getList: () => [ds1],
     getInstanceSettings: () => ds1,
+    get: () =>
+      Promise.resolve({
+        filterQuery: () => true,
+        getDefaultQuery: () => ({
+          expr: 'vector(1)',
+        }),
+      }),
   };
 }