Updating preconfigured connector name (#211927)

## Summary

Update Preconfigured connector name to `Elastic LLM`.

<img width="1504" alt="Screenshot 2025-02-20 at 11 29 02 AM"
src="https://github.com/user-attachments/assets/aa0a32f7-f1b2-4496-8c2e-7773f017c153"
/>

### ES3 Testing instruction
No additional config needed. Once run in local machine, the changes
should reflect automatically.

### ESS instructions
In `kibana.dev.yml` file, add
```
# xpack.actions.preconfigured:
   Elastic-LLM:
     name: Elastic LLM
     actionTypeId: .inference
     exposeConfig: true
     config:
       provider: 'elastic'
       taskType: 'chat_completion'
       inferenceId: '.rainbow-sprinkles-elastic'
       providerConfig:
         model_id: 'rainbow-sprinkles'
```
and the preconfigured endpoint with updated name should be visible.

### Checklist

Check the PR satisfies following conditions. 

Reviewers should verify this PR satisfies this list as well.

- [X] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

config/serverless.yml

@@ -271,13 +271,10 @@ xpack.dataUsage.enabled: true
 # This feature is disabled in Serverless until fully tested within a Serverless environment
 xpack.dataUsage.enableExperimental: ['dataUsageDisabled']
 
-# This feature is disabled in Serverless until Inference Endpoint become enabled within a Serverless environment
-xpack.stack_connectors.enableExperimental: ['inferenceConnectorOff']
-
 # This is the definition introducing pre-configured Kibana Connector for Elastic default LLM
 xpack.actions.preconfigured:
-  Elastic-Inference-Rainbow-Sprinkles:
-    name: Elastic-Inference-Rainbow-Sprinkles
+  Elastic-LLM:
+    name: Elastic LLM
     actionTypeId: .inference
     exposeConfig: true
     config:

x-pack/platform/plugins/shared/fleet/cypress/tasks/api_calls/connectors.ts

@@ -25,7 +25,7 @@ export const request = <T = unknown>({
     ...options,
   });
 };
-export const INTERNAL_INFERENCE_CONNECTORS = ['Elastic-Inference-Rainbow-Sprinkles'];
+export const INTERNAL_INFERENCE_CONNECTORS = ['Elastic-LLM'];
 export const INTERNAL_CLOUD_CONNECTORS = ['Elastic-Cloud-SMTP'];
 
 export const getConnectors = () =>

x-pack/solutions/security/plugins/security_solution/public/management/cypress/tasks/insights.ts

@@ -17,7 +17,7 @@ import {
 } from '../../../../common/endpoint/constants';
 
 const INTERNAL_CLOUD_CONNECTORS = ['Elastic-Cloud-SMTP'];
-const INTERNAL_INFERENCE_CONNECTORS = ['Elastic-Inference-Rainbow-Sprinkles'];
+const INTERNAL_INFERENCE_CONNECTORS = ['Elastic-LLM'];
 const INTERNAL_CONNECTORS = [...INTERNAL_CLOUD_CONNECTORS, ...INTERNAL_INFERENCE_CONNECTORS];
 
 export const createBedrockAIConnector = (connectorName?: string) =>

x-pack/test/security_solution_cypress/cypress/tasks/api_calls/common.ts

@@ -26,7 +26,7 @@ export const API_HEADERS = Object.freeze({
 });
 
 export const INTERNAL_CLOUD_CONNECTORS = ['Elastic-Cloud-SMTP'];
-export const INTERNAL_INFERENCE_CONNECTORS = ['Elastic-Inference-Rainbow-Sprinkles'];
+export const INTERNAL_INFERENCE_CONNECTORS = ['Elastic-LLM'];
 
 export const rootRequest = <T = unknown>({
   headers: optionHeaders = {},