Root CA Validation different from base Docker image behaviour

### Current Behavior

When I add custom certificates (via a Kubernetes init container) and mount /etc/ssl/certs into the keycloak-config-cli container in the same Pod, the extra certificates are not recognized by Java and therefore the connection to Keycloak fails. Putting KEYCLOAK_SSL_VERIFY is not a good solutions though.

### Expected Behavior

Implement the behaviour of the base image, which has the environment variable "USE_SYSTEM_CA_CERTS" to import the certificates already registered with the operating system. (e.g. https://github.com/adoptium/containers/blob/main/21/jre/alpine/3.21/entrypoint.sh#L32)

Explicitly setting

> command: ["/__cacert_entrypoint.sh"]
> args: ["/opt/java/openjdk/bin/java", "-jar", "/app/keycloak-config-cli.jar"]

and therefore overriding `ENTRYPOINT exec java $JAVA_OPTS -jar /app/keycloak-config-cli.jar $0 $@` works for my use case, but having a built-in solution for this issue would be greatly appreciated.

### Steps To Reproduce

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### Environment

- Keycloak Version: [26.1.0]
- keycloak-config-cli Version: [6.4.0]
- Java Version: [21]

### Anything else?

_No response_