…efix

applyClusterPluginBackup preserves the serverName already on the Cluster, so
that a backup does not flip the archive prefix mid-stream. It read that value
through the manager's cached client, and this controller registers
For(&BackupJob{}) and nothing else, so a Cluster only reaches the cache
through a lazily started informer with no resync tied to its own changes.

An in-place RestoreJob deletes the Cluster and the chart re-renders it with
bootstrap.newServerName seconds later. A read served during that window
describes the object that was purged, so the source's serverName is written
back over the freshly rendered one and the restored cluster archives onto the
source's WAL prefix. barman-cloud-check-wal-archive then refuses to start with
"Expected empty archive" and the RestoreJob ends on its deadline -- the
failure newServerName was added to prevent.

The stale read carries a stale UID too, and that UID owns the ObjectStore this
function applies, so the store is garbage-collected as soon as it is written.

Reading through the dynamic client keeps the preservation rule and makes the
value it rests on truthful.

Assisted-by: LLM
Signed-off-by: Mattia Eleuteri <[email protected]>
(cherry picked from commit 67bf9ca)
Signed-off-by: Myasnikov Daniil <[email protected]>