Normally, when a node is shutting down, `gate_closed_exception` and `rpc::closed_error`
in `send_to_live_endpoints` should be ignored. However, if these exceptions are wrapped
in a `nested_exception`, an error message is printed, causing tests to fail.
This commit adds handling for nested exceptions in this case to prevent unnecessary
error messages.
Fixesscylladb/scylladb#23325