[Security Solution] - remove alerts subfeature UI from behind feature flag (#108450)

### Summary
This removes the feature flag check for showing the alerts subfeature under security solution Kibana roles UI.

x-pack/plugins/security_solution/server/features.ts

@@ -76,7 +76,7 @@ export const getAlertsSubFeature = (ruleTypes: string[]): SubFeatureConfig => ({
             all: [],
             read: [],
           },
-          ui: [],
+          ui: ['crud_alerts', 'read_alerts'],
         },
         {
           id: 'alerts_read',
@@ -93,17 +93,14 @@ export const getAlertsSubFeature = (ruleTypes: string[]): SubFeatureConfig => ({
             all: [],
             read: [],
           },
-          ui: [],
+          ui: ['read_alerts'],
         },
       ],
     },
   ],
 });
 
-export const getKibanaPrivilegesFeaturePrivileges = (
-  ruleTypes: string[],
-  isRuleRegistryEnabled: boolean
-): KibanaFeatureConfig => ({
+export const getKibanaPrivilegesFeaturePrivileges = (ruleTypes: string[]): KibanaFeatureConfig => ({
   id: SERVER_APP_ID,
   name: i18n.translate('xpack.securitySolution.featureRegistry.linkSecuritySolutionTitle', {
     defaultMessage: 'Security',
@@ -117,9 +114,7 @@ export const getKibanaPrivilegesFeaturePrivileges = (
   },
   alerting: ruleTypes,
   cases: [APP_ID],
-  subFeatures: isRuleRegistryEnabled
-    ? [{ ...CASES_SUB_FEATURE }, { ...getAlertsSubFeature(ruleTypes) }]
-    : [{ ...CASES_SUB_FEATURE }],
+  subFeatures: [{ ...CASES_SUB_FEATURE }, { ...getAlertsSubFeature(ruleTypes) }],
   privileges: {
     all: {
       app: [APP_ID, 'kibana'],

x-pack/plugins/security_solution/server/plugin.ts

@@ -310,9 +310,7 @@ export class Plugin implements IPlugin<PluginSetup, PluginStart, SetupPlugins, S
       ...(isRuleRegistryEnabled ? racRuleTypes : []),
     ];
 
-    plugins.features.registerKibanaFeature(
-      getKibanaPrivilegesFeaturePrivileges(ruleTypes, isRuleRegistryEnabled)
-    );
+    plugins.features.registerKibanaFeature(getKibanaPrivilegesFeaturePrivileges(ruleTypes));
 
     // Continue to register legacy rules against alerting client exposed through rule-registry
     if (this.setupPlugins.alerting != null) {

x-pack/test/api_integration/apis/security/privileges.ts

@@ -32,7 +32,16 @@ export default function ({ getService }: FtrProviderContext) {
             actions: ['all', 'read'],
             stackAlerts: ['all', 'read'],
             ml: ['all', 'read'],
-            siem: ['all', 'read', 'minimal_all', 'minimal_read', 'cases_all', 'cases_read'],
+            siem: [
+              'all',
+              'read',
+              'minimal_all',
+              'minimal_read',
+              'cases_all',
+              'cases_read',
+              'alerts_all',
+              'alerts_read',
+            ],
             observabilityCases: ['all', 'read'],
             uptime: ['all', 'read'],
             infrastructure: ['all', 'read'],