Fix test data to use consistent script names

Use natural script names (한글, 漢字) and a common accented
word (café) for UTF-8 encoding test data.

Author: xxxxxxjun

mcp-test/src/test/java/io/modelcontextprotocol/server/transport/StdioServerTransportProviderTests.java

@@ -139,7 +139,7 @@ void shouldHandleIncomingMessages() throws Exception {
 	@SuppressWarnings("unchecked")
 	void shouldHandleUtf8EncodedMessages() throws Exception {
 
-		String utf8Content = "한글 테스트 🎉 café 日本語";
+		String utf8Content = "한글 漢字 café 🎉";
 		String jsonMessage = "{\"jsonrpc\":\"2.0\",\"method\":\"test\"," + "\"params\":{\"message\":\"" + utf8Content
 				+ "\"},\"id\":1}\n";
 		InputStream stream = new ByteArrayInputStream(jsonMessage.getBytes(StandardCharsets.UTF_8));