Make Javadoc -1.1 switch related warning conditional again

This commit reverts the behavior introduced in d3fbbda, after which a warning about the `-1.1` switch appears unconditionally.
The warning, "Javadoc 1.4+ doesn't support the -1.1 switch anymore. Ignore this option." now only displays if the `old` parameter is set to true, as it did previously.

Author: perceptron8

src/main/java/org/apache/maven/plugins/javadoc/AbstractJavadocMojo.java

@@ -4324,7 +4324,7 @@ private void addJavadocOptions(
 
         // all options in alphabetical order
 
-        if (getLog().isWarnEnabled()) {
+        if (old && getLog().isWarnEnabled()) {
             getLog().warn("Javadoc 1.4+ doesn't support the -1.1 switch anymore. Ignore this option.");
         }