fix(valkey)!: migrate to valkey/valkey (#1097)

Migrate from bitnamicharts/valkey (and bitnamicharts/valkey-cluster) to the official Valkey Helm chart (https://valkey.io/valkey-helm, v0.10.0).

Changes:
- Remove valkey-cluster dependency and all related values, templates, and unit tests
- Update valkey dependency to use https://valkey.io/valkey-helm
- Adapt _helpers.tpl (valkey.dns, valkey.port, valkey.servicename) to the new chart's service naming and value structure
- Update values.yaml to match the new chart's configuration schema (auth.aclUsers instead of global.valkey.password, service.port instead of primary.service.ports.valkey, dataStorage instead of
  primary.persistence)
- Update all affected unit tests
- Update README documentation

BREAKING CHANGE: valkey-cluster support has been removed. Users previously relying on valkey-cluster must migrate to standalone valkey or an external Redis-compatible service. The valkey values structure
has changed: `valkey.global.valkey.password` is now `valkey.auth.aclUsers.default.password`, and `valkey.primary.service.ports.valkey` is now `valkey.service.port`.

---------

Co-authored-by: rishub <183523+rishub@noreply.gitea.com>
Co-authored-by: rishub <itsrishub@gmail.com>
Reviewed-on: https://gitea.com/gitea/helm-gitea/pulls/1097
Co-authored-by: Markus Pesch <markus.pesch@cryptic.systems>

.gitea/workflows/test-pr.yml

@@ -22,6 +22,11 @@ jobs:
           apk update
           apk add --update bash make nodejs npm yamllint ncurses
       - uses: actions/checkout@v7.0.0
+      - name: define helm repositories
+        run: |
+          helm repo add bitnami https://charts.bitnami.com/bitnami
+          helm repo add valkey https://valkey.io/valkey-helm
+          helm repo update
       - name: install chart dependencies
         run: helm dependency build
       - name: lint