KAFKA-6997: Exclude test-sources.jar when $INCLUDE_TEST_JARS is FALSE
KAFKA-6997: Exclude test-sources.jar when $INCLUDE_TEST_JARS is FALSE

Exclude test-sources.jar when $INCLUDE_TEST_JARS is FALSE

Author: Magesh Nandakumar <magesh.n.kumar@gmail.com>

Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Robert Yokota <rayokota@gmail.com>, Arjun Satish <arjun@confluent.io>, Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>

Closes #5139 from mageshn/KAFKA-6997

ollie314/kafka,Chasego/kafka,lindong28/kafka,Chasego/kafka,mihbor/kafka,sslavic/kafka,KevinLiLu/kafka,richhaase/kafka,apache/kafka,apache/kafka,TiVo/kafka,Chasego/kafka,sslavic/kafka,lindong28/kafka,mihbor/kafka,noslowerdna/kafka,sslavic/kafka,KevinLiLu/kafka,ollie314/kafka,apache/kafka,Ishiihara/kafka,KevinLiLu/kafka,mihbor/kafka,richhaase/kafka,Ishiihara/kafka,noslowerdna/kafka,noslowerdna/kafka,ollie314/kafka,Esquive/kafka,apache/kafka,gf53520/kafka,lindong28/kafka,gf53520/kafka,Ishiihara/kafka,guozhangwang/kafka,TiVo/kafka,noslowerdna/kafka,Esquive/kafka,richhaase/kafka,mihbor/kafka,guozhangwang/kafka,ollie314/kafka,TiVo/kafka,TiVo/kafka,Esquive/kafka,Chasego/kafka,gf53520/kafka,guozhangwang/kafka,Esquive/kafka,lindong28/kafka,richhaase/kafka,KevinLiLu/kafka,guozhangwang/kafka,sslavic/kafka,gf53520/kafka,Ishiihara/kafka