Change return type for VirtualThreadsInfo.getMounted() to int

See gh-43941

Signed-off-by: Johnny Lim <izeye@naver.com>

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/info/ProcessInfo.java

@@ -151,7 +151,7 @@ public class ProcessInfo {
 			this.poolSize = poolSize;
 		}
 
-		public long getMounted() {
+		public int getMounted() {
 			return this.mounted;
 		}