refactor: Remove calls to StartShutdown from KernelNotifications

Use SignalInterrupt object instead. There is a slight change in behavior here
because the previous StartShutdown code used to abort on failure and the
new code logs errors instead.

src/node/kernel_notifications.h

@@ -16,6 +16,10 @@ class CBlockIndex;
 enum class SynchronizationState;
 struct bilingual_str;
 
+namespace util {
+class SignalInterrupt;
+} // namespace util
+
 namespace node {
 
 static constexpr int DEFAULT_STOPATHEIGHT{0};
@@ -23,7 +27,7 @@ static constexpr int DEFAULT_STOPATHEIGHT{0};
 class KernelNotifications : public kernel::Notifications
 {
 public:
-    KernelNotifications(std::atomic<int>& exit_status) : m_exit_status{exit_status} {}
+    KernelNotifications(util::SignalInterrupt& shutdown, std::atomic<int>& exit_status) : m_shutdown(shutdown), m_exit_status{exit_status} {}
 
     [[nodiscard]] kernel::InterruptResult blockTip(SynchronizationState state, CBlockIndex& index) override;
 
@@ -42,6 +46,7 @@ public:
     //! Useful for tests, can be set to false to avoid shutdown on fatal error.
     bool m_shutdown_on_fatal_error{true};
 private:
+    util::SignalInterrupt& m_shutdown;
     std::atomic<int>& m_exit_status;
 };