docs/zh_CN: Remove obsolete translation file

This translation file was replaced by
   Documentation/translations/zh_CN/admin-guide/security-bugs.rst
which was created in commit 2d15357 ("docs/zh_CN: Add
zh_CN/admin-guide/security-bugs.rst").
This is a translation left over from history. Remove it.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Acked-by: Wu XiangCheng <bobwxc@email.cn>
Link: https://lore.kernel.org/r/20210508030741.82655-1-wanjiabing@vivo.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>