[ZEPPELIN-6406] Add commons-logging to Flink lib for YARN integration tests

Flink 1.19+ no longer bundles commons-logging in its distribution, but
Hadoop's FileSystem class requires it. This caused NoClassDefFoundError
for org.apache.commons.logging.LogFactory in FlinkIntegrationTest119/120.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jongyoul

zeppelin-test/src/main/java/org/apache/zeppelin/test/DownloadUtils.java

@@ -509,6 +509,11 @@ public static String downloadFlink(String flinkVersion, String scalaVersion) {
           "https://repo1.maven.org/maven2/org/apache/hadoop/hadoop-client-runtime/3.3.6/hadoop-client-runtime-3.3.6.jar",
           3, new File(targetFlinkHomeFolder,
               "lib" + File.separator + "hadoop-client-runtime-3.3.6.jar"));
+      // commons-logging is required by Hadoop's FileSystem but not bundled in Flink 1.19+
+      download(
+          "https://repo1.maven.org/maven2/commons-logging/commons-logging/1.2/commons-logging-1.2.jar",
+          3, new File(targetFlinkHomeFolder,
+              "lib" + File.separator + "commons-logging-1.2.jar"));
       download("https://repo1.maven.org/maven2/org/apache/flink/flink-table-api-scala_"
           + scalaVersion + "/"
                       + flinkVersion + "/flink-table-api-scala_" + scalaVersion + "-" + flinkVersion + ".jar",