YARN-7995. Remove unnecessary boxings and unboxings from PlacementConstraintParser.java. Contributed by Sen Zhao.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/util/constraint/PlacementConstraintParser.java

@@ -431,10 +431,10 @@ public final class PlacementConstraintParser {
       }
 
       String maxCardinalityStr = resetElements.pop();
-      Integer max = toInt(maxCardinalityStr);
+      int max = toInt(maxCardinalityStr);
 
       String minCardinalityStr = resetElements.pop();
-      Integer min = toInt(minCardinalityStr);
+      int min = toInt(minCardinalityStr);
 
       ArrayList<String> targetTags = new ArrayList<>();
       while (!resetElements.empty()) {