[MINOR] Drop the duplicate xtable-core test-jar dependency (#899)

xtable-utilities declared it twice, identically, which Maven warns about
and says future versions may reject.

Author: slachiewicz

xtable-utilities/pom.xml

@@ -244,14 +244,6 @@
             <artifactId>junit-jupiter-engine</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.apache.xtable</groupId>
-            <artifactId>xtable-core_${scala.binary.version}</artifactId>
-            <version>${project.version}</version>
-            <classifier>tests</classifier>
-            <type>test-jar</type>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.apache.hudi</groupId>
             <artifactId>hudi-spark${spark.version.prefix}-bundle_${scala.binary.version}</artifactId>