add namespace environment variable back

Signed-off-by: Chengwei Guo <chengweiguo@bytedance.com>

Author: cw-Guo

config/manager/manager.yaml

@@ -48,6 +48,12 @@ spec:
             port: 8081
           initialDelaySeconds: 5
           periodSeconds: 10
+        env:
+          - name: NAMESPACE
+            valueFrom:
+              fieldRef:
+                apiVersion: v1
+                fieldPath: metadata.namespace
         resources:
           limits:
             cpu: 200m

manifests/setup/setup.yaml

@@ -41828,6 +41828,12 @@ spec:
         - --metrics-bind-address=:8443
         command:
         - /manager
+        env:
+        - name: NAMESPACE
+          valueFrom:
+            fieldRef:
+              apiVersion: v1
+              fieldPath: metadata.namespace
         image: ghcr.io/fluent/fluent-operator/fluent-operator:latest
         livenessProbe:
           httpGet: