`value` field in User CRD Password spec is unusable due to valueFrom being unconditionally required

[dvdlevanon]

Description

The Password spec for the User CRD documents two valid ways to provide a password:

Redpanda users require a password, which you can provide directly, using the spec.password.value field, or through a Kubernetes Secret, using the spec.password.valueFrom.secretKeyRef.

However, using value alone is impossible in practice because the OpenAPI schema marks valueFrom as unconditionally required, causing the webhook to reject the manifest before any validation logic runs.

Steps to Reproduce

apiVersion: cluster.redpanda.com/v1alpha2
kind: User
metadata:
  name: test-user
  namespace: redpanda
spec:
  cluster:
    clusterRef:
      name: redpanda
  authentication:
    type: scram-sha-256
    password:
      value: test

kubectl apply -f test.yaml

Error

The User "test-user" is invalid:
* spec.authentication.password.valueFrom: Required value
* <nil>: Invalid value: null: some validation rules were not checked because the object was invalid; correct the existing errors to complete validation