upgrade junit to 5 or not?

**Is your feature request related to a problem? Please describe.**

Does need to upgrade junit 4 to junit 5?

See #4193 if we upgrade the project's test to junit 5, some test feature like `@Nested` annotation can be used.

**Describe the solution you'd like**
* change the maven dependencies
* change the import in java code
* change the ci

**Additional context**

awaitility use junit 4, see
https://github.com/apolloconfig/apollo/blob/master/pom.xml#L282-L285
```java

org.awaitility
awaitility
test

```
We need to investigate that awaitility can use junit 5 or not.