fix(redis): run the multi-arch redis_exporter so the sidecar starts on arm64 (#4522)

## What this PR does

Redis and Valkey instances, and the Redis inside Harbor, never become
fully ready on arm64 nodes. Their failovers pin
`oliver006/redis_exporter:v1.55.0-alpine`, which upstream publishes for
amd64 only. On arm64 the exporter sidecar exits with `exec
/redis_exporter: exec format error`, and the pod stays not ready.

The same release without the suffix is a multi-arch index with amd64,
arm and arm64 builds. Its entrypoint, user and port match the `-alpine`
image, and none of these charts run a shell in the exporter container.
So this swaps the tag and pins it by digest, with no version bump.

I checked both tags with `crane`. On an arm64 test cluster a Redis and a
Valkey instance hit the exec format error before the change and came up
2/2 with it. The Harbor Redis pods went to 2/2 the same way.

On upgrade the exporter image in the pod template changes, so the
operator rolls every Redis and Valkey instance and Harbor's Redis, one
pod at a time as it does for any failover update.

Fixes #4519

### Screenshots

No UI changes.

### Downstream repositories

- [x] No downstream repository is affected by this change
- [ ] [cozystack/website](https://github.com/cozystack/website) -
follow-up:
- [ ]
[cozystack/terraform-provider-cozystack](https://github.com/cozystack/terraform-provider-cozystack)
- follow-up:
- [ ]
[cozystack/ansible-cozystack](https://github.com/cozystack/ansible-cozystack)
- follow-up:
- [ ] [cozystack/ccp](https://github.com/cozystack/ccp) - follow-up:
- [ ] [cozystack/talm](https://github.com/cozystack/talm) - follow-up:
- [ ] [cozystack/cozyhr](https://github.com/cozystack/cozyhr) -
follow-up:
- [ ] [cozystack/cozy-proxy](https://github.com/cozystack/cozy-proxy) -
follow-up:
- [ ]
[cozystack/cozystack-telemetry-server](https://github.com/cozystack/cozystack-telemetry-server)
- follow-up:
- [ ]
[cozystack/external-apps-example](https://github.com/cozystack/external-apps-example)
- follow-up:
- [ ] [cozystack/examples](https://github.com/cozystack/examples) -
follow-up:
- [ ] [cozystack/community](https://github.com/cozystack/community) -
follow-up:

The diff changes one image reference in three templates. No entry in the
trigger map covers a sidecar image.

### Release note

```release-note
fix(redis): Redis, Valkey and Harbor's Redis now use the multi-arch redis_exporter image, so the exporter sidecar starts on arm64 nodes.
```

packages/apps/redis/templates/redisfailover.yaml

@@ -75,7 +75,7 @@ spec:
     {{- end }}
     exporter:
       enabled: true
-      image: oliver006/redis_exporter:v1.55.0-alpine
+      image: oliver006/redis_exporter:v1.55.0@sha256:d82625bda93823fb40de881ffbb45b65aca772a39c30141387f92314c258da5d
       args:
         - --web.telemetry-path
         - /metrics

packages/apps/valkey/templates/valkeyfailover.yaml

@@ -56,7 +56,7 @@ spec:
     {{- end }}
     exporter:
       enabled: true
-      image: oliver006/redis_exporter:v1.55.0-alpine
+      image: oliver006/redis_exporter:v1.55.0@sha256:d82625bda93823fb40de881ffbb45b65aca772a39c30141387f92314c258da5d
       args:
         - --web.telemetry-path
         - /metrics

packages/system/harbor/templates/redis.yaml

@@ -61,7 +61,7 @@ spec:
           {{- end }}
     exporter:
       enabled: true
-      image: oliver006/redis_exporter:v1.55.0-alpine
+      image: oliver006/redis_exporter:v1.55.0@sha256:d82625bda93823fb40de881ffbb45b65aca772a39c30141387f92314c258da5d
       args:
         - --web.telemetry-path
         - /metrics