Add junit5 test code for module [linkis-engineconn-manager-server]

### Add junit5 test code for module [linkis-engineconn-manager-server]
- Module: linkis-engineconn-manager-server
- Location: linkis-computation-governance/linkis-engineconn-manager-server
- Task status:✗(unfinished)/ ✓(finished)
- Test code guide:https://linkis.apache.org/zh-CN/community/how-to-write-unit-test-code/
- Test code example: https://github.com/apache/incubator-linkis/tree/master/linkis-public-enhancements/linkis-publicservice/linkis-jobhistory/src/test
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- 模块名: linkis-engineconn-manager-server
- 代码位置: linkis-computation-governance/linkis-engineconn-manager-server
- 任务状态:✗(unfinished)/ ✓(finished)
- 单测编写指引:https://linkis.apache.org/zh-CN/community/how-to-write-unit-test-code/
- 参考样例: https://github.com/apache/incubator-linkis/tree/master/linkis-public-enhancements/linkis-publicservice/linkis-jobhistory/src/test

| Task status| Class | Type| Level of Difficulty | Note |
| :------ | :------ | :------: | :------: | :------: |
| ✗ |org.apache.linkis.ecm.server.converter.ECMEngineConverter| Converter | normal | |
| ✗ |org.apache.linkis.ecm.server.exception.ECMErrorException| Exception| normal | |
| ✗ |org.apache.linkis.ecm.server.hook.JarUDFLoadECMHook| Hook| normal | |
| ✗ |org.apache.linkis.ecm.server.metrics.DefaultECMMetrics| Metrics| normal | |
| ✗ |org.apache.linkis.ecm.server.operator.*| Operator| normal | |
| ✗ |org.apache.linkis.ecm.server.service.impl.*| Service| normal | |
| ✗ |org.apache.linkis.ecm.server.util.*| Utils| normal | |