Remove @since tags from internal classes

Internal classes are not used by external artifacts and their Javadoc is not published.

Author: ppkarwasz

log4j-api-java9/src/main/java/org/apache/logging/log4j/util/internal/DefaultObjectInputFilter.java

@@ -21,9 +21,6 @@
 
 import java.io.ObjectInputFilter;
 
-/**
- * @since 2.11.0
- */
 public class DefaultObjectInputFilter implements ObjectInputFilter {
 
     private final ObjectInputFilter delegate;

log4j-api/src/main/java/org/apache/logging/log4j/internal/LogManagerStatus.java

@@ -18,8 +18,6 @@
 
 /**
  * Keeps track of LogManager initialization status;
- *
- * @since 2.14.1
  */
 public class LogManagerStatus {