update: 删除流量路由部分

[rootsongjc]

「Sidecar 注入及透明流量劫持」被拆分为两篇文章了。

提交 PR 后请先自查以下内容：

• PR 的标题格式为：在空白文档中新增内容 add: 文档标题，修改已有内容的文档 update：文档标题。
• 在该 PR 已指明解决的 issue 链接：无
• 已阅读并保证所提交 PR 符合写作规范。
• 文章内容格式请参考 PR add: practice/jwt-authorization #186。
• 保留下文中的声明。

声明

• 我认可本书的版权信息：本书著作权归属于 ServiceMesher 社区，我将保留对所修改内容的署名权。

• 我已阅读参与贡献说明，并加入了 istio-handbook-wg GitHub team。

[mesher-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rootsongjc

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