[Fleet] fix fleet_list_agent tests (#241289)

## Summary

Closes #170690


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Author: juliaElastic

x-pack/platform/test/fleet_api_integration/apis/agents/list.ts

@@ -19,8 +19,7 @@ export default function ({ getService }: FtrProviderContext) {
   const mockAgentlessApiService = setupMockServer();
   let elasticAgentpkgVersion: string;
 
-  // FLAKY: https://github.com/elastic/kibana/issues/170690
-  describe.skip('fleet_list_agent', () => {
+  describe('fleet_list_agent', () => {
     let mockApiServer: http.Server;
 
     before(async () => {
@@ -323,18 +322,6 @@ export default function ({ getService }: FtrProviderContext) {
     });
 
     it('should not return agentless agents when showAgentless=false', async () => {
-      // Set up default Fleet Server host, needed during agentless agent creation
-      await supertest
-        .post(`/api/fleet/fleet_server_hosts`)
-        .set('kbn-xsrf', 'xxxx')
-        .send({
-          id: 'fleet-default-fleet-server-host',
-          name: 'Default',
-          is_default: true,
-          host_urls: ['https://test.com:8080', 'https://test.com:8081'],
-        })
-        .expect(200);
-
       // Create an agentless agent policy
       const { body: policyRes } = await supertest
         .post('/api/fleet/agent_policies')

x-pack/platform/test/fleet_api_integration/config.agent.ts

@@ -9,12 +9,23 @@ import type { FtrConfigProviderContext } from '@kbn/test';
 
 export default async function ({ readConfigFile }: FtrConfigProviderContext) {
   const baseFleetApiConfig = await readConfigFile(require.resolve('./config.base.ts'));
+  const baseConfig = baseFleetApiConfig.getAll();
 
   return {
-    ...baseFleetApiConfig.getAll(),
+    ...baseConfig,
     testFiles: [require.resolve('./apis/agents')],
     junit: {
       reportName: 'X-Pack Fleet Agent API Integration Tests',
     },
+    kbnTestServer: {
+      ...baseConfig.kbnTestServer,
+      serverArgs: [
+        ...baseConfig.kbnTestServer.serverArgs,
+        // Add cloud configuration specifically for agent tests (needed for agentless functionality in ESS)
+        `--xpack.cloud.id="ftr_fake_cloud_id:aGVsbG8uY29tOjQ0MyRFUzEyM2FiYyRrYm4xMjNhYmM="`,
+        `--xpack.cloud.base_url="https://cloud.elastic.co"`,
+        `--xpack.cloud.deployment_url="/deployments/deploymentId"`,
+      ],
+    },
   };
 }