[FTR] Unskiped test (elastic#235064)

## Summary

Unskiped FTR test.



__Closes: https://github.com/elastic/kibana/issues/235052__

Author: elena-shostak

src/platform/test/plugin_functional/test_suites/core_plugins/rendering.ts

@@ -72,8 +72,7 @@ export default function ({ getService }: PluginFunctionalProviderContext) {
       return window.__RENDERING_SESSION__;
     });
 
-  // Failing: See https://github.com/elastic/kibana/issues/235052
-  describe.skip('rendering service', () => {
+  describe('rendering service', () => {
     it('exposes plugin config settings to authenticated users', async () => {
       // This retry loop to get the injectedMetadata is to overcome flakiness
       // (see comment in getInjectedMetadata)
@@ -387,6 +386,7 @@ export default function ({ getService }: PluginFunctionalProviderContext) {
         'xpack.observabilityAiAssistantManagement.spacesEnabled (boolean?)',
         'xpack.observabilityAiAssistantManagement.visibilityEnabled (boolean?)',
         'xpack.observabilityShared.unsafe.investigativeExperienceEnabled (boolean?)',
+        'xpack.observability.managedOtlpServiceUrl (string?)',
         'share.new_version.enabled (boolean?)',
         'aiAssistantManagementSelection.preferredAIAssistantType (default?|never?|observability?|security?)',
         'xpack.genAiSettings.showAiBreadcrumb (boolean?)',