Update test/jdk/java/net/UnixDomainSocketAddress/LengthTest.java

Co-authored-by: Marcono1234 <Marcono1234@users.noreply.github.com>

Author: dfuch

test/jdk/java/net/UnixDomainSocketAddress/LengthTest.java

@@ -51,9 +51,9 @@ public static List<String> strings() {
 
         return List.of(
                 "",
-                new String(new char[100]).replaceAll("\0", "x"),
-                new String(new char[namelen]).replaceAll("\0", "x"),
-                new String(new char[namelen-1]).replaceAll("\0", "x")
+                "x".repeat(100),
+                "x".repeat(namelen),
+                "x".repeat(namelen - 1)
         );
     }