fix(_get_keyspaces_to_decrease_rf): Address a case where no keyspace …

…RF value of DC

In case no keyspace replication-factor value is retrieved in a DC,
A warning is logged and the keyspace is ignored (skipped).
Fixes: #8694

sdcm/utils/replication_strategy_utils.py

@@ -180,8 +180,12 @@ def _get_keyspaces_to_decrease_rf(self, session) -> list:
                 continue  # Skip keyspace using SimpleStrategy
 
             if 'NetworkTopologyStrategy' in replication['class']:
-                rf = int(replication.get(self.datacenter))
-                if rf == self.original_nodes_number:
+                rf = replication.get(self.datacenter)
+                if rf is None:
+                    LOGGER.warning(
+                        f"Datacenter {self.datacenter} not found in replication strategy for keyspace {keyspace_name}.")
+                    continue
+                if int(rf) == self.original_nodes_number:
                     matching_keyspaces.append(keyspace_name)
             else:
                 LOGGER.warning("Unexpected replication strategy found: %s", replication['class'])