Ignore unmanaged namespaces in webhook validation for all resources.

[naemono]

closes #5814

Allow non-Elasticsearch resources outside of managed namespaces to also be ignored by webhooks.

Testing

Ran with version/values:

managedNamespaces:
- default
image:
  repository: docker.elastic.co/eck-dev/eck-operator-mmontgomery
  tag: 2.5.0-SNAPSHOT-6288a5b0

When applying the following manifest:

apiVersion: beat.k8s.elastic.co/v1beta1
kind: Beat
metadata:
  name: heartbeat
  namespace: elastic
spec:
  type: heartbeat
  version: 8.2.3
  elasticsearchRef:
    name: elasticsearch
  config:
    heartbeat.monitors:
    - type: tcp
      schedule: '@every 5s'
      hosts: ["elasticsearch-es-http.default.svc:9200"]
  deployment:
    replicas: 1

You can see the operator's webhook validation ignoring this resource.

[elastic-operator-0] {"log.level":"debug","@timestamp":"2022-09-13T20:55:15.492Z","log.logger":"controller-runtime.webhook.webhooks","message":"received request","service.version":"2.5.0-SNAPSHOT+6288a5b0","service.type":"eck","ecs.version":"1.4.0","webhook":"/validate-beat-k8s-elastic-co-v1beta1-beat","UID":"3e2be798-0bae-4fd7-a6f1-bc5d98adbcc8","kind":"beat.k8s.elastic.co/v1beta1, Kind=Beat","resource":{"group":"beat.k8s.elastic.co","version":"v1beta1","resource":"beats"}}
[elastic-operator-0] {"log.level":"debug","@timestamp":"2022-09-13T20:55:15.493Z","log.logger":"common-webhook","message":"Skip resource validation","service.version":"2.5.0-SNAPSHOT+6288a5b0","service.type":"eck","ecs.version":"1.4.0","name":"heartbeat","namespace":"elastic"}
[elastic-operator-0] {"log.level":"debug","@timestamp":"2022-09-13T20:55:15.493Z","log.logger":"controller-runtime.webhook.webhooks","message":"wrote response","service.version":"2.5.0-SNAPSHOT+6288a5b0","service.type":"eck","ecs.version":"1.4.0","webhook":"/validate-beat-k8s-elastic-co-v1beta1-beat","code":200,"reason":"","UID":"3e2be798-0bae-4fd7-a6f1-bc5d98adbcc8","allowed":true}

[naemono]

run/e2e-tests

[thbkrkr]

LGTM