style: enable HideUtilityClassConstructor in checkstyle (#5147)

src/test/java/com/thealgorithms/datastructures/trees/TreeTestUtils.java

@@ -4,7 +4,9 @@ import com.thealgorithms.datastructures.trees.BinaryTree.Node;
 import java.util.LinkedList;
 import java.util.Queue;
 
-public class TreeTestUtils {
+public final class TreeTestUtils {
+    private TreeTestUtils() {
+    }
 
     /**
      * Creates a binary tree with given values

src/test/java/com/thealgorithms/others/ArrayRightRotation.java

@@ -1,6 +1,8 @@
 package com.thealgorithms.others;
 
-public class ArrayRightRotation {
+public final class ArrayRightRotation {
+    private ArrayRightRotation() {
+    }
     public static int[] rotateRight(int[] arr, int k) {
         if (arr == null || arr.length == 0 || k < 0) {
             throw new IllegalArgumentException("Invalid input");

src/test/java/com/thealgorithms/others/CRC16Test.java

@@ -5,9 +5,6 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import org.junit.jupiter.api.Test;
 
 class CRC16Test {
-
-    CRC16 crc = new CRC16();
-
     @Test
     void testCRC16() {
         // given

src/test/java/com/thealgorithms/strings/IsomorphicTest.java

@@ -5,7 +5,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
-public class IsomorphicTest {
+public final class IsomorphicTest {
+    private IsomorphicTest() {
+    }
 
     @Test
     public static void main(String[] args) {

src/test/java/com/thealgorithms/strings/ReverseStringRecursiveTest.java

@@ -5,8 +5,6 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import org.junit.jupiter.api.Test;
 
 public class ReverseStringRecursiveTest {
-    ReverseStringRecursive stringRecursive = new ReverseStringRecursive();
-
     @Test
     void shouldAcceptWhenEmptyStringIsPassed() {
         String expected = "";