add unit test, delete helloworld project

[TremblingV5]

Link to an issue

What

1. 增加一个单元测试
2. 增加consul默认配置
3. 删除helloworld项目

How

Screenshots

How to test

Checklist

• Link to an issue if it really related.
• At least describe what this PR does.
• Use rebase to confirm that current branch doesn't conflict with main branch.
• Unit tests. At least do not reduce the unit test coverage.
• Checked and updated guidelines.md which used to describe how to build, deploy and use DouTok.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/gopkgs/components/consulx/config.go	0.00%	3 Missing ⚠️

Files with missing lines	Coverage Δ
backend/gopkgs/components/consulx/config.go	0.00% <0.00%> (ø)