This PR refactors excluded nodes handling for tablets and topology. For tablets a dedicated variable `topology::excluded_tablet_nodes` is introduced, for topology operations a method get_excluded_nodes() is inlined into topology_coordinator and renamed to `get_excluded_nodes_for_topology_request`.
The PR improves codes readability and efficiency, no behavior changes.
backport: this is a refactoring/optimization, no need to backport
Closesscylladb/scylladb#26907
* https://github.com/scylladb/scylladb:
topology_coordinator: drop unused exec_global_command overload
topology_coordinator: rename get_excluded_nodes -> get_excluded_nodes_for_topology_request
topology_state_machine: inline get_excluded_nodes
messaging_service: simplify and optimize ban_host
storage_service: topology_state_load: extract topology variable
topology_coordinator: excluded_tablet_nodes -> ignored_nodes
topology_state_machine: add excluded_tablet_nodes field
1141342c4f