Revert "HADOOP-16822. Provide source artifacts for hadoop-client-api. Contributed by Karel Kolman." (#6458)

This reverts commit 2c4ab72a60113e4dd4ef2375e6f9413e519b1044.

Justification: this was making debugging through IDEs worse, rather than better.

hadoop-client-modules/hadoop-client-api/pom.xml

@@ -94,10 +94,6 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-shade-plugin</artifactId>
-            <configuration>
-              <createSourcesJar>true</createSourcesJar>
-              <shadeSourcesContent>true</shadeSourcesContent>
-            </configuration>
             <dependencies>
               <dependency>
                 <groupId>org.apache.hadoop</groupId>