MXS-1775 Remove destroy()

Now the instance is deleted simply by deleting it.

server/modules/monitor/mariadbmon/mariadbmon.hh

@@ -42,6 +42,8 @@ private:
 public:
     // TODO: Once done refactoring, see which of these can be moved to private.
 
+    ~MariaDBMonitor();
+
     /**
      * Print diagnostics.
      *
@@ -78,11 +80,6 @@ public:
      */
     bool start(const MXS_CONFIG_PARAMETER* params);
 
-    /**
-     * Destroyes aka deletes the instance.
-     */
-    void destroy();
-
     /**
      * Stop the monitor. Waits until monitor has stopped.
      */
@@ -171,7 +168,6 @@ private:
 
     // Base methods
     MariaDBMonitor(MXS_MONITOR* monitor_base);
-    ~MariaDBMonitor();
     void reset_server_info();
     void clear_server_info();
     bool load_config_params(const MXS_CONFIG_PARAMETER* params);