[image_nodelet] change destroyWindow() to destroyAllWindows()

[nakane11]

When image_view window is closed wirh "x" button, cv::Exception is thrown and the node cannot successfully be killed:

terminate called after throwing an instance of 'cv::Exception'
  what():  OpenCV(4.2.0) ../modules/highgui/src/window_gtk.cpp:1260: error: (-215:Assertion failed) found && "Can't destroy non-registered window" in function 'cvDestroyWindow'

[image_view00-5] process has died [pid 3148875, exit code -6, cmd /home/nakane/ros/catkin_ws/devel/lib/image_view/image_view image:=tile_image_2x1/output __name:=image_view00 __log:=/home/nakane/.ros/log/20230517-160130_a69074d6-f480-11ed-9b90-0b32d9e34b63/image_view00-5.log].

I replaced cv::destroyWindow(window_name_) with cv::destroyAllWindows() to avoid destroying windows that no longer exist.