Multiple executors does not work when Airflow is deployed in kubernetes

### Under which category would you file this issue?

Helm chart

### Apache Airflow version

Helm chart 1.22 / Airflow 3.3.0

### What happened and how to reproduce it?

Hello Team,
I have deployed Airflow 3.3.0 in kubernetes and configured the executor Kubernetes executor. Then Airflow was working well and my dags were running in separated pods.

Then I wanted to prepare the use of the new feature called multiple executors.
So, in my dags, I have set executor="KubernetesExecutor" in the task properties.
As a consequence, it returns this error :
UnknownExecutorException: Task 'sync_associations_group.get_data' specifies executor 'KubernetesExecutor', which is not available. Make sure it is listed in your [core] executors configuration, or update the task's executor to use one of the configured executors

I have listed the executor in the executor helm chart property, then I tried in the config.core.executors property, then in config.core.executor property.
Unfortunately it fails every time with the same error.
I have verified the airflow-config configmap and it is correct.

### What you think should happen instead?

It should run my airflow task successfully.

### Operating System

Kubernetes / Official apache/airflow image

### Deployment

Official Apache Airflow Helm Chart

### Apache Airflow Provider(s)

_No response_

### Versions of Apache Airflow Providers

I use the versions from the file https://raw.githubusercontent.com/apache/airflow/constraints-3.3.0/constraints-3.14.txt
and the following providers:
apache-airflow-providers-cncf-kubernetes
apache-airflow-providers-amazon
apache-airflow-providers-opensearch
apache-airflow-providers-http
apache-airflow-providers-common-sql
apache-airflow-providers-postgres

### Official Helm Chart version

1.22.0 (latest released)

### Kubernetes Version

1.33

### Helm Chart configuration

executor: "KubernetesExecutor"
config:
core:
default_timezone: "Europe/Paris"
test_connection: "Enabled"
executors: "KubernetesExecutor"
kubernetes_executor:
worker_container_repository: registry.dso.interieur.rie.gouv.fr/mi-hubassociations/img-airflow-worker
worker_container_tag: *tag_airflow_worker

### Docker Image customizations

_No response_

### Anything else?

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start by reproducing the failure with the provided Official Apache Airflow Helm Chart 1.22.0 configuration and inspect the generated airflow-config ConfigMap, especially the core executors setting. Compare that configuration with the task-level KubernetesExecutor selection; done means a task using multiple executors is accepted and runs successfully in its expected pod.

Written by the indexing model from the issue text.