fix(deploy): do not provide a default namespace

kustomization.yaml

@@ -1,13 +1,9 @@
 apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
-namespace: airflow
 
 generatorOptions:
   disableNameSuffixHash: true
 
-resources:
-- ./resources/namespace.yaml
-
 components:
 - ./components/airflow-cnpg-database
 
@@ -22,7 +18,6 @@ helmCharts:
   repo: https://airflow.apache.org
   version: 1.9.0
   releaseName: airflow
-  namespace: airflow
   valuesInline:
     postgresql:
       enabled: false