tools/utils: configure_tool_mode: set auto_handle_sigint_sigterm = false

Disable seastar's built in handlers for SIGINT and SIGTERM and thus
fall-back to the OS's default handlers, which terminate the process.
This makes tool applications interruptable by SIGINT and SIGTERM.
The default handler just terminates the tool app immediately and
doesn't allow for cleanup, but this is fine: the tools have no important
data to save or any critical cleanup to do before exiting.

Fixes: scylladb/scylladb#16954

Closes scylladb/scylladb#22838

tools/utils.cc

@@ -140,6 +140,10 @@ const operation* get_selected_operation(int& ac, char**& av, const std::vector<o
 // Set ERROR as the default log level, except for the logger \p logger_name, which
 // is configured with INFO level.
 void configure_tool_mode(app_template::seastar_options& opts, const sstring& logger_name) {
+    // Disable handling of SIGINT/SIGTERM by seastar, allow the tool to be
+    // interrupted by way of not handling these signals.
+    opts.auto_handle_sigint_sigterm = false;
+
     opts.reactor_opts.blocked_reactor_notify_ms.set_value(60000);
     opts.reactor_opts.overprovisioned.set_value();
     opts.reactor_opts.idle_poll_time_us.set_value(0);