[UII] Remove system-managed properties (dates) when updating index templates

x-pack/platform/plugins/shared/fleet/common/types/models/epm.ts

@@ -768,6 +768,13 @@ export interface IndexTemplate {
   composed_of: string[];
   ignore_missing_component_templates?: string[];
   _meta: object;
+
+  // These properties are returned on ES read operations and
+  // not allowed to be set on ES write operations
+  created_date?: number;
+  created_date_millis?: number;
+  modified_date?: number;
+  modified_date_millis?: number;
 }
 
 export interface ESAssetMetadata {

x-pack/platform/plugins/shared/fleet/server/services/package_policies/experimental_datastream_features.ts

@@ -199,8 +199,17 @@ export async function handleExperimentalDatastreamFeatureOptIn({
       });
     }
 
-    const indexTemplate = indexTemplateRes.index_templates[0].index_template;
-    let updatedIndexTemplate = indexTemplate as IndexTemplate;
+    const rawIndexTemplate = indexTemplateRes.index_templates[0].index_template;
+
+    // Remove system-managed properties (dates) that cannot be set during create/update of index templates
+    const {
+      created_date: createdDate,
+      created_date_millis: createdDateMillis,
+      modified_date: modifiedDate,
+      modified_date_millis: modifiedDateMillis,
+      ...indexTemplate
+    } = rawIndexTemplate as IndexTemplate;
+    let updatedIndexTemplate = indexTemplate;
 
     if (isTSDBOptInChanged) {
       const indexTemplateBody = {

x-pack/platform/test/fleet_api_integration/apis/epm/data_stream.ts

@@ -192,8 +192,7 @@ export default function (providerContext: FtrProviderContext) {
         await installPackage(pkgName, pkgUpdateVersion);
       });
 
-      // FAILING ES PROMOTION: https://github.com/elastic/kibana/issues/230902
-      describe.skip('When enabling experimental data stream features', () => {
+      describe('When enabling experimental data stream features', () => {
         let agentPolicyId: string;
         let packagePolicyId: string;