fix: exclude the Kotlin sample from Maven Central publishing

The module has no Java sources, so maven-javadoc-plugin attaches no
javadoc jar to it and Central rejects the whole deployment with
"Javadocs must be provided but not found in entries", which is what
broke the 5.5.1 release. It only exists as a Kotlin interop E2E test,
so keep it out of the published bundle.

Author: csviri

sample-operators/kotlin-operator/pom.xml

@@ -34,6 +34,7 @@
 
   <properties>
     <kotlin.version>2.4.10</kotlin.version>
+    <skipPublishing>true</skipPublishing>
   </properties>
 
   <dependencyManagement>