Remove unnecessary code (#4141)

src/main/java/com/thealgorithms/datastructures/heaps/FibonacciHeap.java

@@ -234,7 +234,6 @@ public class FibonacciHeap {
         if (!curr.isMarked()) { //stop the recursion
             curr.mark();
             if (!curr.isRoot()) this.markedHeapNoodesCounter++;
-            return;
         } else {
             if (curr.isRoot()) {
                 return;

src/main/java/com/thealgorithms/datastructures/heaps/MinPriorityQueue.java

@@ -51,18 +51,12 @@ public class MinPriorityQueue {
 
     // returns boolean value whether the heap is empty or not
     public boolean isEmpty() {
-        if (0 == this.size) {
-            return true;
-        }
-        return false;
+        return 0 == this.size;
     }
 
     // returns boolean value whether the heap is full or not
     public boolean isFull() {
-        if (this.size == this.capacity) {
-            return true;
-        }
-        return false;
+        return this.size == this.capacity;
     }
 
     // prints the heap