fix(update-db-packages): stop only updated nodes

When updating multiple nodes db packages, SCT stops all the nodes.
This is wrong and causes tests to fail when providing
`update_db_packages` param.

Fix by removing broken logic and dropping code for nodes stop ordering.

fixes: #8551
(cherry picked from commit c140e7b)

sdcm/cluster.py

@@ -4212,26 +4212,10 @@ def start_scylla(node):
 
         start_time = time.time()
 
-        if len(node_list) == 1:
-            # Stop only new nodes
-            self.run_func_parallel(func=stop_scylla, node_list=node_list)  # pylint: disable=no-member
-            # Then, update packages only on requested node
-            self.run_func_parallel(func=update_scylla_packages, node_list=node_list)  # pylint: disable=no-member
-            if start_service:
-                # Start new nodes
-                self.run_func_parallel(func=start_scylla, node_list=node_list)  # pylint: disable=no-member
-        else:
-            # First, stop *all* non seed nodes
-            self.run_func_parallel(func=stop_scylla, node_list=self.non_seed_nodes)  # pylint: disable=no-member
-            # First, stop *all* seed nodes
-            self.run_func_parallel(func=stop_scylla, node_list=self.seed_nodes)  # pylint: disable=no-member
-            # Then, update packages only on requested nodes
-            self.run_func_parallel(func=update_scylla_packages, node_list=node_list)  # pylint: disable=no-member
-            if start_service:
-                # Start all seed nodes
-                self.run_func_parallel(func=start_scylla, node_list=self.seed_nodes)  # pylint: disable=no-member
-                # Start all non seed nodes
-                self.run_func_parallel(func=start_scylla, node_list=self.non_seed_nodes)  # pylint: disable=no-member
+        self.run_func_parallel(func=stop_scylla, node_list=node_list)  # pylint: disable=no-member
+        self.run_func_parallel(func=update_scylla_packages, node_list=node_list)  # pylint: disable=no-member
+        if start_service:
+            self.run_func_parallel(func=start_scylla, node_list=node_list)  # pylint: disable=no-member
 
         time_elapsed = time.time() - start_time
         self.log.debug('Update DB packages duration -> %s s', int(time_elapsed))