[wpimath] Use UtilityClassTest for more utility classes (#5384)

wpimath/src/main/java/edu/wpi/first/math/DARE.java

@@ -7,7 +7,9 @@ package edu.wpi.first.math;
 import org.ejml.simple.SimpleMatrix;
 
 public final class DARE {
-  private DARE() {}
+  private DARE() {
+    throw new UnsupportedOperationException("This is a utility class!");
+  }
 
   /**
    * Solves the discrete algebraic Riccati equation.

wpimath/src/main/java/edu/wpi/first/math/StateSpaceUtil.java

@@ -15,7 +15,7 @@ public final class StateSpaceUtil {
   private static Random rand = new Random();
 
   private StateSpaceUtil() {
-    // Utility class
+    throw new UnsupportedOperationException("This is a utility class!");
   }
 
   /**