YARN-10809. Missing dependency causing NoClassDefFoundError in TestHBaseTimelineStorageUtils (#3081)

Reviewed-by: Takanobu Asanuma <tasanuma@apache.org>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/pom.xml

@@ -110,6 +110,12 @@
       <artifactId>hadoop-yarn-server-timelineservice</artifactId>
     </dependency>
 
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <scope>test</scope>
+    </dependency>
+
     <dependency>
       <groupId>org.apache.hbase</groupId>
       <artifactId>hbase-common</artifactId>