ci: clean up tests.

[youngsofun]

1. use testng`s own asserts, reduce unnecessary test deps.
2. rm deps Gson.
3. unify test group name to uppercase.

[youngsofun]

cc @hantmac

Run jwgmeligmeyling/checkstyle-github-action@master
  with:
    path: **/checkstyle-result.xml
    token: ***
    name: Checkstyle Report
    title: Checkstyle Results
  env:
    JAVA_HOME: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/11.0.28-6/x64
    JAVA_HOME_11_X64: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/11.0.28-6/x64
With the provided path, there will be 2 results uploaded
Creating annotations for /home/runner/work/databend-jdbc/databend-jdbc/databend-client/target/checkstyle-result.xml
Creating annotations for /home/runner/work/databend-jdbc/databend-jdbc/databend-jdbc/target/checkstyle-result.xml
Uploading 0 / 0 annotations to GitHub as Checkstyle Report with conclusion success
Error: HttpError: Resource not accessible by integration