Replaced StringBuffer with StringBuilder in PageCommand (#540)

Co-authored-by: opencode-agent[bot] <opencode-agent[bot]@users.noreply.github.com>
Co-authored-by: LSantha <LSantha@users.noreply.github.com>

Author: opencode-agent[bot]

cli/src/commands/org/jnode/command/system/PageCommand.java

@@ -365,7 +365,7 @@ private void searchForwards() throws IOException {
      * @throws IOException
      */
     private String readLine(int ch) throws IOException {
-        StringBuffer sb = new StringBuffer();
+        StringBuilder sb = new StringBuilder();
         String line;
         do {
             sb.append((char) ch);