improvement(xcloud): add update_cluster_name method

[Copilot]

Description

Adds ability to modify cluster name after deployment for managing keep/owner tags.

Changes

• New method: ScyllaCloudCluster.update_cluster_name(new_name: str)
  • Validates cluster ID exists and name ≤ 63 chars
  • Updates via existing API client method
  • Syncs local cluster.name attribute
• Unit tests: 3 test cases covering success path, error handling, and edge cases

Usage

# Add keep tag
cluster.update_cluster_name("my-cluster-abc12345-keep-24h")

# Remove keep tag  
cluster.update_cluster_name("my-cluster-abc12345")

Uses updateClusterName API endpoint.

Testing

• Unit tests added (test_cluster_cloud.py::TestScyllaCloudClusterUpdateName)
• changing a cluster name in runtime:

>>> self._api_client.get_cluster_details(account_id=self._account_id, cluster_id=self._cluster_id)['clusterName']
'PR-provision-test-dmytro_kruglov-d2aa4594-keep-004h'

>>> self.update_cluster_name('new_cluster_name')
< t:2026-01-13 00:09:11,723 f:cluster_cloud.py l:976  c:sdcm.cluster         p:INFO  > ScyllaCloudCluster:db-cluster-d2aa4594: Updating cluster name from 'db-cluster-d2aa4594' to 'new_cluster_name'
< t:2026-01-13 00:09:12,131 f:cluster_cloud.py l:981  c:sdcm.cluster         p:INFO  > ScyllaCloudCluster:db-cluster-d2aa4594: Cluster name updated successfully to 'new_cluster_name'

>>> self._api_client.get_cluster_details(account_id=self._account_id, cluster_id=self._cluster_id)['clusterName']
'new_cluster_name'

PR pre-checks (self review)

• I added the relevant backport labels
• I didn't leave commented-out/debugging code

Reminders

• Add New configuration option and document them (in sdcm/sct_config.py)
• Add unit tests to cover my changes (under unit-test/ folder)
• Update the Readme/doc folder relevant to this change (if needed)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[scylla-cloud] add ability to modify name of a live cluster</issue_title>
<issue_description>We need to be able to update name of a cluster after it is deployed, e.g. for the purpose of adding or deleting keep and/or owner tags info. https://cloud.docs.scylladb.com/stable/api.html#tag/Cluster/operation/updateClusterName public API method should be used for that.

We can add a new method to sdcm.cluster_cloud.ScyllaCloudCluster, or a new hydra command, or both.</issue_description>

<agent_instructions>Implement the change name method for cluster object, no need for hydra command for now.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes scylladb/qa-tasks#2007

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[fruch]

I would assume we now can implement those two ?

    # For cloud clusters, the keep duration is calculated and set during cluster creation.
    # _set_keep_alive and _set_keep_duration methods in base classes are invoked after cluster
    # creation, during nodes init, when it is already late to modify cluster details.
    # The basic implementations of these methods remain here for backward compatibility.
    def _set_keep_alive(self) -> bool:
        return True

    def _set_keep_duration(self, duration_in_hours: int) -> None:
        pass

since we are using are using poorsman tagging within the name

[dimakr]

I wonder if we should touch these.
first - these methods are on the node level in base classes, and for xcloud cluster we do not / cannot manage names of individual nodes, only of the whole cluster.

If we implement these helpers somehow for cluster level, it would not bring much value - it would rather add additional API requests, as cluster name is set during initial cloud cluster create API request anyway. With these 2 implemented for xcloud we would be doing extra API requests to achieve the same result we have now.

but the main concern - it's better to set keep-Nh tag earlier in the test, so that if something bad happens between cluster creation (that would interrupt the test completely) and the moment we run init on SCT objects (like these 2 methods are used now in the base classes), we already have cluster prepared/named for automated cleanup