feat: switch valkey dependency to official valkey-io chart

[ppawlowski]

Description

This pull request replaces the valkey chart dependency from CloudPirates (oci://registry-1.docker.io/cloudpirates, version 0.15.3) with the official valkey-io/valkey-helm chart (https://valkey.io/valkey-helm/, version 0.9.4).

Motivation: CloudPirates have announced the deprecation of their Valkey chart in CloudPirates-io/helm-charts#1083 and recommend the upstream chart as the replacement.

NOTE: the information below about chart behaviour with default and custom values will be added to the README file after the release.

Behaviour for default values

• forge.localValkey: true with the valkey: block at defaults: transparent upgrade.
• The workload kind changes StatefulSet → Deployment (the official chart uses a Deployment for standalone mode).
• Service name, port, and DNS hostname are unchanged (<release>-valkey:6379).

Behaviour for custom valkey: overrides

Upstream uses a different values schema. Users who override keys under valkey: need to translate them:

Old (CloudPirates)	New (valkey-io)
valkey.persistence.enabled	valkey.dataStorage.enabled
valkey.persistence.size	valkey.dataStorage.requestedSize
valkey.persistence.storageClass	valkey.dataStorage.className
valkey.config.maxMemory	line inside valkey.valkeyConfig raw string
valkey.config.maxMemoryPolicy	line inside valkey.valkeyConfig raw string
valkey.config.save	line inside valkey.valkeyConfig raw string
valkey.replicaCount	valkey.replica.replicas (with valkey.replica.enabled: true)
valkey.architecture	valkey.replica.enabled (sentinel mode is no longer supported)
valkey.auth.password	valkey.auth.aclUsers.default.password (ACL model)

Related Issue(s)

Closes #882

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production
• Link to Changelog Entry PR, or note why one is not needed.

Labels

• Includes a DB migration? -> add the area:migration label

[hardillb]

I'll try and test this today