disable WAL archiving not work as indicated on administrator.md guide

• Which image of the operator are you using? ghcr.io/zalando/spilo-15:2.1-p9
• Where do you run it - cloud or metal? Kubernetes or OpenShift? AWS EKS
• Are you running Postgres Operator in production? [yes]
• Type of issue? [Bug report]

From the doc
Or you want to disable WAL archiving for a certain cluster by setting WAL_S3_BUCKET, WAL_GS_BUCKET or AZURE_STORAGE_ACCOUNT to an empty string.

My postgresql-cluster manifest:

apiVersion: "acid.zalan.do/v1"
kind: "postgresql"
metadata:
  name: "cl1-postgresql"
  namespace: "infra"
  labels:
    team: cl1
spec:
  env:
  - name: wal_s3_bucket
    value: ""
  dockerImage: ghcr.io/zalando/spilo-15:3.0-p1
  teamId: "cl1"
  postgresql:
    version: "12"
  numberOfInstances: 3
  volume:
    size: "20G"
    storageClass: "gp2"
  users:
    {}
  databases:
    {}
  resources:
    limits:
      cpu: 500m
      memory: 500Mi
    requests:
      cpu: 10m
      memory: 100Mi
  patroni:
    initdb:
      encoding: "UTF-8"
      locale: "en_US.UTF-8"
      data-checksums: "true"
    ttl: 30
    loop_wait: &loop_wait 10

I expect that WAL archive is disabled but it works and creates files in the local data filesystem under pg_wal directory.

Start with administrator.md and the supplied PostgreSQL manifest, focusing on the WAL_S3_BUCKET setting and the operator's handling of an empty value. Reproduce the configuration on Kubernetes and inspect the resulting WAL archiving behavior. Done means the documented setting and actual behavior agree, with the guide or configuration handling corrected accordingly.