[FLINK-25039][build] Disable shading of test jar by default

diff --git a/flink-sql-connector-kafka/pom.xml b/flink-sql-connector-kafka/pom.xml
index d58f2e3..c26142b 100644
--- a/flink-sql-connector-kafka/pom.xml
+++ b/flink-sql-connector-kafka/pom.xml
@@ -56,7 +56,6 @@
 							<goal>shade</goal>
 						</goals>
 						<configuration>
-							<shadeTestJar>false</shadeTestJar>
 							<artifactSet>
 								<includes>
 									<include>org.apache.kafka:*</include>