Fix Tomcat's maxConnections default value

Closes gh-19472

Author: snicoll

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -372,7 +372,7 @@ public static class Tomcat {
 		 * given time. Once the limit has been reached, the operating system may still
 		 * accept connections based on the "acceptCount" property.
 		 */
-		private int maxConnections = 10000;
+		private int maxConnections = 8192;
 
 		/**
 		 * Maximum queue length for incoming connection requests when all possible request