fix(helm): mark filer db-init ConfigMap volume optional (#10596)

The filer StatefulSet declares db-schema-config-volume unconditionally, referencing <release>-seaweedfs-db-init-config. The chart never renders that ConfigMap and the README documents it as operator-supplied, so any deployment that has not pre-created it ends up with a pod spec pointing at a non-existent object. No container mounts the volume, so this is currently inert, but it is misleading and would become a pod-start failure if a volumeMount is ever added.

k8s/charts/seaweedfs/templates/filer/filer-statefulset.yaml

@@ -356,6 +356,7 @@ spec:
         - name: db-schema-config-volume
           configMap:
             name: {{ default (printf "%s-db-init-config" (include "seaweedfs.fullname" .)) .Values.filer.dbInitConfigName }}
+            optional: true
         {{- if and .Values.filer.s3.enabled .Values.filer.s3.enableAuth }}
         - name: config-users
           secret: