docs(sample): use Java 8 for native image sample (#1060)

Author: mpeddada1

samples/native-image-sample/pom.xml

@@ -20,8 +20,8 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
   </parent>
 
   <properties>
-    <maven.compiler.target>11</maven.compiler.target>
-    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
+    <maven.compiler.source>1.8</maven.compiler.source>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>