Ensure the operator detects that it supports the amd64 architecture

We have seen the operator spew errors of the type

{
  "level": "error",
  "ts": "2024-08-05T08:08:18Z",
  "msg": "Reconciler error",
  "controller": "cluster",
  "controllerGroup": "postgresql.cnpg.io",
  "controllerKind": "Cluster",
  "Cluster": {
    "name": "pgcluster-example",
    "namespace": "pgcluster-test"
  },
  "namespace": "pgcluster-test",
  "name": "pgcluster-example",
  "reconcileID": "445640b8-7aca-4875-9452-e0c3993ab7d6",
  "error": "cannot update the resource status: invalid architecture: amd64",
  "stacktrace": "..."
}

After a bit of digging in the opertor code, I found the /manager debug show-architectures command. When running it in the official cloudnative-pg image, we see the following:

~ ❯ docker run --rm -it 5aaf1300ccd5 debug show-architectures
[
    "amd64",
    "arm64"
]

However, when running this command in the image we built, we see an empty list:

~ ❯ docker run --rm -it docker-registry.wikimedia.org/repos/data-engineering/postgresql-kubernetes/cloudnative-pg:1.23.1 debug show-architectures
[]

I read the operator code, and found this section, that showed that the supported archiitectures are detected at runtime, by looking at the suffixes the /bin/manager_* symmlinks, all pointing to /manager.

I inspected both images using dive, and indeed, our image didn't have any symlink named /bin/manager_amd64 pointing to /manager.

(Our image is in the top pane, and the official image in the bottom one)

Bug: T364797