[Task] Improve test case coverage

[moremind]

Description

Improve test case coverage for shenyu-client, shenyu-admin, shenyu-bootstrap, shenyu-sync, shenyu-integrated-test, please commit your pull request about this issue or at me.

Task List

1.shenyu-admin
2.shenyu-bootstrap
3.shenyu-sync
4.shenyu-client

Result

Coverage： 80%

[MoyunF]

Hello, I want to participate in the Shenyu community. Can you assign me the task of the shenyu-sync?

[liuhuijuan12]

Hello, I want to participate in the Shenyu community. Can you assign me the task of the shenyu-sync?

[whenelse]

Hello, I want to participate in the Shenyu community. Can you assign me the task of the shenyu-admin?

[zhengkezhou1]

Hello, I want to participate in the Shenyu community. Can you assign me the task of the shenyu-admin?

[Cyoking]

Hello, I want to participate in the Shenyu community. Can you assign me the task of the shenyu-client?

[kamiingithub]

@moremind
Hello, I want to participate in the Shenyu community. Can you assign me the task of the shenyu-sync?