[Kibana]: Missing mappings for Stack Monitoring

### Integration Name

Kibana [kibana]

### Dataset Name

kibana.stack_monitoring.stats

### Integration Version

Latest

### Agent Version

8.18.8

### Agent Output Type

elasticsearch

### Elasticsearch Version

8.18.4

### OS Version and Architecture

Windows Server 2019 Standard / kernel: 10.0.17763.7786 / build: 17763.7792

### Software/API Version

Kibana 8.18.4

### Error Message

_No response_

### Event Original

_No response_

### What did you do?

The Elasticsearch, Kibana and Logstash stack components were upgraded to 8.18.4 and in the process their monitoring changed from the Metricbeat `kibana` module to the Elastic Agent `kibana` integration.

### What did you see?

The Stack Monitoring UI stopped showing Kibana metrics as soon as Kibana started to be monitored by the Elastic Agent.

### What did you expect to see?

The expectation was for the migration from Beats to the Elastic Agent to be transparent and the Stack Monitoring UI to keep showing Kibana metrics.

### Anything else?

After a first investigation, it seems that the data stream mappings in the `kibana` integration don't contain the field aliases expected by the Stack Monitoring UI.