[hotfix] Set TestProcess logging to DEBUG

This commit changes CommonTestUtils.printLog4jDebugConfig to set the log level to DEBUG
for easier debugging of failed tests that use the TestProcess.

flink-runtime/src/test/java/org/apache/flink/runtime/testutils/CommonTestUtils.java

@@ -114,7 +114,7 @@ public static String getJavaCommandPath() {
 
     public static void printLog4jDebugConfig(File file) throws IOException {
         try (PrintWriter writer = new PrintWriter(new FileWriter(file))) {
-            writer.println("rootLogger.level = INFO");
+            writer.println("rootLogger.level = DEBUG");
             writer.println("rootLogger.appenderRef.console.ref = ConsoleAppender");
             writer.println("appender.console.name = ConsoleAppender");
             writer.println("appender.console.type = CONSOLE");