scripts: Remove the "show-fixed-bugs.sh" file

Since we are not using Launchpad anymore, there is no more need for
this script.

Message-Id: <20210825142143.142037-1-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Thomas Huth <thuth@redhat.com>