Migrate /test/apm_api_integration/tests/span_links to be deployment-a…

…gnostic API tests (#200140)

closes #198990
part of #193245

### 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"
```

- 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"
```

-
[MKI](https://github.com/crespocarlos/kibana/blob/main/x-pack/test_serverless/README.md#run-tests-on-mki)

### Checklist
- [x] (OPTIONAL, only if a test has been unskipped) Run flaky test suite
- [x] serverless
- [x] stateful
- [x] MKI

---------

Co-authored-by: kibanamachine <[email protected]>

x-pack/test/api_integration/deployment_agnostic/apis/observability/apm/index.ts

@@ -34,5 +34,6 @@ export default function apmApiIntegrationTests({
     loadTestFile(require.resolve('./service_groups'));
     loadTestFile(require.resolve('./diagnostics'));
     loadTestFile(require.resolve('./service_nodes'));
+    loadTestFile(require.resolve('./span_links'));
   });
 }

x-pack/test/api_integration/deployment_agnostic/apis/observability/apm/span_links/index.ts

@@ -0,0 +1,14 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { DeploymentAgnosticFtrProviderContext } from '../../../../ftr_provider_context';
+
+export default function ({ loadTestFile }: DeploymentAgnosticFtrProviderContext) {
+  describe('span_links', () => {
+    loadTestFile(require.resolve('./span_links.spec.ts'));
+  });
+}

x-pack/test/apm_api_integration/tests/span_links/span_links.spec.ts → x-pack/test/api_integration/deployment_agnostic/apis/observability/apm/span_links/span_links.spec.ts

@@ -7,23 +7,24 @@
 import expect from '@kbn/expect';
 import { ProcessorEvent } from '@kbn/observability-plugin/common';
 import { Readable } from 'stream';
-import { FtrProviderContext } from '../../common/ftr_provider_context';
+import type { ApmSynthtraceEsClient } from '@kbn/apm-synthtrace';
+import type { DeploymentAgnosticFtrProviderContext } from '../../../../ftr_provider_context';
 import { generateSpanLinksData } from './data_generator';
 
-export default function ApiTest({ getService }: FtrProviderContext) {
-  const registry = getService('registry');
-  const apmApiClient = getService('apmApiClient');
-  const apmSynthtraceEsClient = getService('apmSynthtraceEsClient');
+export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderContext) {
+  const apmApiClient = getService('apmApi');
+  const synthtrace = getService('synthtrace');
 
   const start = new Date('2022-01-01T00:00:00.000Z').getTime();
   const end = new Date('2022-01-01T00:15:00.000Z').getTime() - 1;
 
-  // FLAKY: https://github.com/elastic/kibana/issues/177520
-  registry.when('contains linked children', { config: 'basic', archives: [] }, () => {
+  describe('contains linked children', () => {
     let ids: ReturnType<typeof generateSpanLinksData>['ids'];
+    let apmSynthtraceEsClient: ApmSynthtraceEsClient;
 
     before(async () => {
       const spanLinksData = generateSpanLinksData();
+      apmSynthtraceEsClient = await synthtrace.createApmSynthtraceEsClient();
 
       ids = spanLinksData.ids;