Exclude JUnit 4 from Hadoop dependencies in HDFS module

The HDFS tests were failing on CI with NoClassDefFoundError for org.junit.Assert
because Hadoop dependencies were bringing in JUnit 4 as a transitive dependency.

Since we've migrated to JUnit 5, we need to exclude JUnit 4 from all Hadoop
dependencies to prevent classpath conflicts.

Changes:
- Added JUnit 4 exclusions to hadoop-hdfs-client dependency
- Added JUnit 4 exclusions to hadoop-common dependency (both regular and test-jar)
- Added JUnit 4 exclusions to hadoop-hdfs dependency (both regular and test-jar)

This ensures that only JUnit 5 (Jupiter) is on the classpath during test execution.

Note: The HDFS module has a pre-existing Maven dependency resolution issue
on some environments that prevents compilation. This is unrelated to the
JUnit migration and exists on the master branch.

Author: gnodet

commons-vfs2-hdfs/pom.xml

@@ -41,14 +41,35 @@
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-hdfs-client</artifactId>
+      <exclusions>
+        <exclusion>
+          <!-- Exclude JUnit 4 - we use JUnit 5 -->
+          <groupId>junit</groupId>
+          <artifactId>junit</artifactId>
+        </exclusion>
+      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-common</artifactId>
+      <exclusions>
+        <exclusion>
+          <!-- Exclude JUnit 4 - we use JUnit 5 -->
+          <groupId>junit</groupId>
+          <artifactId>junit</artifactId>
+        </exclusion>
+      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-hdfs</artifactId>
+      <exclusions>
+        <exclusion>
+          <!-- Exclude JUnit 4 - we use JUnit 5 -->
+          <groupId>junit</groupId>
+          <artifactId>junit</artifactId>
+        </exclusion>
+      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.logging.log4j</groupId>
@@ -81,18 +102,30 @@
         <exclusion>
          <!-- VFS-606 - tools.jar not available in Java 9
               This exclusion can be removed after upgrading Hadoop
-              to 2.7.1 or later  
+              to 2.7.1 or later
           -->
           <groupId>jdk.tools</groupId>
           <artifactId>jdk.tools</artifactId>
         </exclusion>
+        <exclusion>
+          <!-- Exclude JUnit 4 - we use JUnit 5 -->
+          <groupId>junit</groupId>
+          <artifactId>junit</artifactId>
+        </exclusion>
       </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-hdfs</artifactId>
       <type>test-jar</type>
       <scope>test</scope>
+      <exclusions>
+        <exclusion>
+          <!-- Exclude JUnit 4 - we use JUnit 5 -->
+          <groupId>junit</groupId>
+          <artifactId>junit</artifactId>
+        </exclusion>
+      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.mockito</groupId>