[APM] Migrate service group alert test (elastic#200789)

closes elastic#198982

## Summary

Migrates a test covering alerts on service group feature. It's possible
to migrate it with `alertingApi` service.


### How to test

- Serverless

```
node scripts/functional_tests_server --config x-pack/test/api_integration/deployment_agnostic/configs/serverless/oblt.serverless.config.ts
node scripts/functional_test_runner --config x-pack/test/api_integration/deployment_agnostic/configs/serverless/oblt.serverless.config.ts --grep="APM"
```

It's recommended to be run against
[MKI](https://github.com/crespocarlos/kibana/blob/main/x-pack/test_serverless/README.md#run-tests-on-mki)

- Stateful
```
node scripts/functional_tests_server --config x-pack/test/api_integration/deployment_agnostic/configs/stateful/oblt.stateful.config.ts
node scripts/functional_test_runner --config x-pack/test/api_integration/deployment_agnostic/configs/stateful/oblt.stateful.config.ts --grep="APM"
```

- [ ] ~(OPTIONAL, only if a test has been unskipped) Run flaky test
suite~
- [x] local run for serverless
- [x] local run for stateful
- [x] MKI run for serverless

x-pack/test/api_integration/deployment_agnostic/apis/observability/apm/service_groups/service_group_count/service_group_count.spec.ts

@@ -6,24 +6,32 @@
  */
 import expect from '@kbn/expect';
 import type { ApmSynthtraceEsClient } from '@kbn/apm-synthtrace';
+import type { RoleCredentials } from '@kbn/ftr-common-functional-services';
+import { ApmRuleType } from '@kbn/rule-data-utils';
+import { AggregationType } from '@kbn/apm-plugin/common/rules/apm_rule_types';
 import type { DeploymentAgnosticFtrProviderContext } from '../../../../../ftr_provider_context';
 import {
   createServiceGroupApi,
   deleteAllServiceGroups,
   getServiceGroupCounts,
 } from '../service_groups_api_methods';
 import { generateData } from './generate_data';
+import { APM_ACTION_VARIABLE_INDEX, APM_ALERTS_INDEX } from '../../alerts/helpers/alerting_helper';
 
 export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderContext) {
   const synthtrace = getService('synthtrace');
   const apmApiClient = getService('apmApi');
+  const alertingApi = getService('alertingApi');
+  const samlAuth = getService('samlAuth');
+
   const start = Date.now() - 24 * 60 * 60 * 1000;
   const end = Date.now();
 
   describe('Service group counts', () => {
     let synthbeansServiceGroupId: string;
     let opbeansServiceGroupId: string;
     let apmSynthtraceEsClient: ApmSynthtraceEsClient;
+    let roleAuthc: RoleCredentials;
 
     before(async () => {
       apmSynthtraceEsClient = await synthtrace.createApmSynthtraceEsClient();
@@ -59,5 +67,50 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
       expect(response.body[synthbeansServiceGroupId]).to.have.property('services', 2);
       expect(response.body[opbeansServiceGroupId]).to.have.property('services', 1);
     });
+
+    describe('with alerts', () => {
+      let ruleId: string;
+
+      before(async () => {
+        roleAuthc = await samlAuth.createM2mApiKeyWithRoleScope('admin');
+        const createdRule = await alertingApi.createRule({
+          name: 'Latency threshold | synth-go',
+          params: {
+            serviceName: 'synth-go',
+            transactionType: undefined,
+            windowSize: 5,
+            windowUnit: 'h',
+            threshold: 100,
+            aggregationType: AggregationType.Avg,
+            environment: 'testing',
+          },
+          ruleTypeId: ApmRuleType.TransactionDuration,
+          consumer: 'apm',
+          roleAuthc,
+        });
+
+        ruleId = createdRule.id;
+        await alertingApi.waitForAlertInIndex({ ruleId, indexName: APM_ALERTS_INDEX });
+      });
+
+      after(async () => {
+        await alertingApi.cleanUpAlerts({
+          roleAuthc,
+          ruleId,
+          alertIndexName: APM_ALERTS_INDEX,
+          connectorIndexName: APM_ACTION_VARIABLE_INDEX,
+          consumer: 'apm',
+        });
+        await samlAuth.invalidateM2mApiKeyWithRoleScope(roleAuthc);
+      });
+
+      it('returns the correct number of alerts', async () => {
+        const response = await getServiceGroupCounts(apmApiClient);
+        expect(response.status).to.be(200);
+        expect(Object.keys(response.body).length).to.be(2);
+        expect(response.body[synthbeansServiceGroupId]).to.have.property('alerts', 1);
+        expect(response.body[opbeansServiceGroupId]).to.have.property('alerts', 0);
+      });
+    });
   });
 }