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>

unittests/helm/dependency-checks/major-image-bump.yaml

@@ -29,24 +29,9 @@ tests:
           path: spec.template.spec.containers[0].image
           # IN CASE OF AN INTENTIONAL MAJOR BUMP, ADJUST THIS TEST
           pattern: bitnamilegacy/postgresql:17.+$
-  - it: "[valkey-cluster] ensures we detect major image version upgrades"
-    template: charts/valkey-cluster/templates/valkey-statefulset.yaml
-    set:
-      valkey-cluster:
-        enabled: true
-      valkey:
-        enabled: false
-    asserts:
-      - documentIndex: 0
-        matchRegex:
-          path: spec.template.spec.containers[0].image
-          # IN CASE OF AN INTENTIONAL MAJOR BUMP, ADJUST THIS TEST
-          pattern: bitnamilegacy/valkey-cluster:8.+$
   - it: "[valkey] ensures we detect major image version upgrades"
-    template: charts/valkey/templates/primary/application.yaml
+    template: charts/valkey/templates/deploy_valkey.yaml
     set:
-      valkey-cluster:
-        enabled: false
       valkey:
         enabled: true
     asserts:
@@ -54,4 +39,4 @@ tests:
         matchRegex:
           path: spec.template.spec.containers[0].image
           # IN CASE OF AN INTENTIONAL MAJOR BUMP, ADJUST THIS TEST
-          pattern: bitnamilegacy/valkey:8.+$
+          pattern: valkey/valkey:9.+$