fix: remove CSI 18t terminal query (read-char-no-hang on fd 0 never returns)

The %query-terminal-size function sent \033[18t and tried to read
the response via read-char-no-hang on fd 0, which always returns nil
in this SBCL environment. The response leaked into user input,
displaying garbled CSI sequences. Rely on ioctl only.

src/backend/simple.lisp

@@ -39,7 +39,6 @@
                  (values (sb-alien:deref winsize 1)
                          (sb-alien:deref winsize 0)))
              (sb-alien:free-alien winsize))))
-      (%query-terminal-size)
       (values 80 24)))
 
 (defmethod backend-write ((b simple-backend) string)