Hide assistant's knowledge base UI when `assistantKnowledgeBaseByDefa…

…ult` feature flag is disabled (elastic#196762)

## Summary

This is the followup to elastic#195733
where we implemented the RBAC to allow managing Global Knowledge Base
docs. With those changes we introduced a bug where we do not hide the
RBAC configuration setting when `assistantKnowledgeBaseByDefault`
feature flag is disabled. It means that in Serverless users will see
this setting but it will do nothing for them.

### Screenshots of the fixed behaviour

* `assistantKnowledgeBaseByDefault = true`

![Capture-2024-10-17-204859](https://github.com/user-attachments/assets/ca4489b1-8ad9-4e57-824f-455ddb74da6c)

* `assistantKnowledgeBaseByDefault = false`

![Capture-2024-10-17-204752](https://github.com/user-attachments/assets/fbd2511f-4e09-4ef9-8403-6578366728e4)

(cherry picked from commit f6e8065)

x-pack/packages/security-solution/features/src/assistant/index.ts

@@ -9,11 +9,13 @@ import type { ProductFeatureParams } from '../types';
 import { getAssistantBaseKibanaFeature } from './kibana_features';
 import {
   getAssistantBaseKibanaSubFeatureIds,
-  assistantSubFeaturesMap,
+  getAssistantSubFeaturesMap,
 } from './kibana_sub_features';
 
-export const getAssistantFeature = (): ProductFeatureParams<AssistantSubFeatureId> => ({
+export const getAssistantFeature = (
+  experimentalFeatures: Record<string, boolean>
+): ProductFeatureParams<AssistantSubFeatureId> => ({
   baseKibanaFeature: getAssistantBaseKibanaFeature(),
   baseKibanaSubFeatureIds: getAssistantBaseKibanaSubFeatureIds(),
-  subFeaturesMap: assistantSubFeaturesMap,
+  subFeaturesMap: getAssistantSubFeaturesMap(experimentalFeatures),
 });

x-pack/packages/security-solution/features/src/assistant/kibana_sub_features.ts

@@ -102,9 +102,28 @@ export const getAssistantBaseKibanaSubFeatureIds = (): AssistantSubFeatureId[] =
  * Defines all the Security Assistant subFeatures available.
  * The order of the subFeatures is the order they will be displayed
  */
-export const assistantSubFeaturesMap = Object.freeze(
-  new Map<AssistantSubFeatureId, SubFeatureConfig>([
+export const getAssistantSubFeaturesMap = (
+  experimentalFeatures: Record<string, boolean>
+): Map<AssistantSubFeatureId, SubFeatureConfig> => {
+  const assistantSubFeaturesList: Array<[AssistantSubFeatureId, SubFeatureConfig]> = [
     [AssistantSubFeatureId.updateAnonymization, updateAnonymizationSubFeature],
-    [AssistantSubFeatureId.manageGlobalKnowledgeBase, manageGlobalKnowledgeBaseSubFeature],
-  ])
-);
+  ];
+
+  // Use the following code to add feature based on feature flag
+  // if (experimentalFeatures.featureFlagName) {
+  //   assistantSubFeaturesList.push([AssistantSubFeatureId.featureId, featureSubFeature]);
+  // }
+
+  if (experimentalFeatures.assistantKnowledgeBaseByDefault) {
+    assistantSubFeaturesList.push([
+      AssistantSubFeatureId.manageGlobalKnowledgeBase,
+      manageGlobalKnowledgeBaseSubFeature,
+    ]);
+  }
+
+  const assistantSubFeaturesMap = new Map<AssistantSubFeatureId, SubFeatureConfig>(
+    assistantSubFeaturesList
+  );
+
+  return Object.freeze(assistantSubFeaturesMap);
+};

x-pack/plugins/security_solution/server/lib/product_features_service/product_features_service.ts

@@ -62,7 +62,7 @@ export class ProductFeaturesService {
       casesFeature.baseKibanaSubFeatureIds
     );
 
-    const assistantFeature = getAssistantFeature();
+    const assistantFeature = getAssistantFeature(this.experimentalFeatures);
     this.securityAssistantProductFeatures = new ProductFeatures(
       this.logger,
       assistantFeature.subFeaturesMap,

x-pack/test/api_integration/config.ts

@@ -30,6 +30,9 @@ export async function getApiIntegrationConfig({ readConfigFile }: FtrConfigProvi
         '--xpack.ruleRegistry.write.enabled=true',
         '--xpack.ruleRegistry.write.enabled=true',
         '--xpack.ruleRegistry.write.cache.enabled=false',
+        `--xpack.securitySolution.enableExperimental=${JSON.stringify([
+          'assistantKnowledgeBaseByDefault',
+        ])}`,
         '--monitoring_collection.opentelemetry.metrics.prometheus.enabled=true',
       ],
     },