Make shading rule consistent between bookkeeper-server-shaded and bookkeeper-server-tests-shaded
Make shading rule consistent between bookkeeper-server-shaded and bookkeeper-server-tests-shaded

Descriptions of the changes in this PR:

`bookkeeper-server:test-jar` is working with `bookkeeper-server`. we should make `bookkeeper-server-tests-shaded` work with `bookkeeper-server-shaded`.  so this change is to make they have consistent shading rule.

```
<dependency>
      <groupId>org.apache.bookkeeper</groupId>
      <artifactId>bookkeeper-server-shaded</artifactId>
      <version>${bookkeeper.version}</version>
      <scope>test</scope>
    </dependency>
<dependency>
      <groupId>org.apache.bookkeeper</groupId>
      <artifactId>bookkeeper-server-tests-shaded</artifactId>
      <version>${bookkeeper.version}</version>
      <scope>test</scope>
    </dependency>
```

Author: Sijie Guo <sijie@apache.org>

Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Matteo Merli <mmerli@apache.org>

This closes #1234 from sijie/sijie_improve_tests_shaded

apache/bookkeeper,sijie/bookkeeper,sijie/bookkeeper,sijie/bookkeeper,apache/bookkeeper,sijie/bookkeeper,apache/bookkeeper,apache/bookkeeper,sijie/bookkeeper,ivankelly/bookkeeper,ivankelly/bookkeeper,apache/bookkeeper,sijie/bookkeeper,ivankelly/bookkeeper,sijie/bookkeeper,apache/bookkeeper,sijie/bookkeeper