[COLLECTIONS-777] Migrate to JUnit 5

Remove redundant constructors

src/test/java/org/apache/commons/collections4/bidimap/DualTreeBidiMap2Test.java

@@ -51,10 +51,6 @@ public class DualTreeBidiMap2Test<K extends Comparable<K>, V extends Comparable<
         }
     }
 
-    public DualTreeBidiMap2Test() {
-        super();
-    }
-
     @Override
     public String getCompatibilityVersion() {
         return "4.Test2";

src/test/java/org/apache/commons/collections4/bidimap/DualTreeBidiMapTest.java

@@ -21,10 +21,6 @@ package org.apache.commons.collections4.bidimap;
  */
 public class DualTreeBidiMapTest<K extends Comparable<K>, V extends Comparable<V>> extends AbstractSortedBidiMapTest<K, V> {
 
-    public DualTreeBidiMapTest() {
-        super();
-    }
-
     /**
      * {@inheritDoc}
      */

src/test/java/org/apache/commons/collections4/bidimap/UnmodifiableSortedBidiMapTest.java

@@ -32,10 +32,6 @@ import org.junit.jupiter.api.Test;
  */
 public class UnmodifiableSortedBidiMapTest<K extends Comparable<K>, V extends Comparable<V>> extends AbstractSortedBidiMapTest<K, V> {
 
-    public UnmodifiableSortedBidiMapTest() {
-        super();
-    }
-
     @Override
     public boolean isAllowNullKey() {
         return false;