[java] Fix 'Hello, World!' case for Java new project sample code

Closes #2458

Signed-off-by: Louis Vignier <Louis.Vignier@jetbrains.com>

GitOrigin-RevId: 70d26ea2241c6eb7d0d33c250d24b11cbc3e2cfc

java/java-impl/src/fileTemplates/internal/SampleCode.java.ft

@@ -5,6 +5,6 @@ package ${PACKAGE_NAME};
 #parse("File Header.java")
 public class Main {
     public static void main(String[] args) {
-        System.out.println("Hello world!");
+        System.out.println("Hello, World!");
     }
 }