The helm-chart should not force the settings of Resultsbackend, Metadata and Broker. Either through an additional configuration option or implicitly by not providing values, the helm-chart should refrain from populating those Airflow-Env configurations.

**Use case / motivation**
The current Helm chart forces the configuration of certain values such as `brokerUrl` (https://github.com/apache/airflow/blob/main/chart/values.yaml#L236)
Which will then be populated as Airflow ENV config.
Due to Airflows configuration precedence (https://airflow.apache.org/docs/apache-airflow/stable/howto/set-config.html) are these settings taking highest priority in Airflow configuration.

With the suggested change, users can dynamically provide Airflow configurations through Airflow's `__CMD` environment variables.

**In other words; provide users with the option to utilize Airflow's `__CMD` ENV configuration.**

_I am willing to submit a PR._

chart/tests/test_airflow_common.py
)
    def test_should_use_correct_image(self, use_default_image, expected_image):
        docs = render_chart(
            values={
                "defaultAirflowRepository": "apache/airflow",
                "defaultAirflowTag": "2.1.0",
                "images": {
                    "airflow": {
                        "repository": "apache/airflow",
                        "tag": "user-image",
                    },
                    "useDefaultImageForMigration": use_default_image,
                },
            },
            show_only=[
                "templates/scheduler/scheduler-deployment.yaml",
                "templates/workers/worker-deployment.yaml",
                "templates/webserver/webserver-deployment.yaml",
                "templates/triggerer/triggerer-deployment.yaml",
            ],
        )
        for doc in docs:
            assert expected_image == jmespath.search("spec.template.spec.initContainers[0].image", doc)
    def test_should_set_correct_helm_hooks_weight(self):
        docs = render_chart(
            show_only=["templates/secrets/fernetkey-secret.yaml"],
        )
        annotations = jmespath.search("metadata.annotations", docs[0])
        assert annotations["helm.sh/hook-weight"] == "0"