CA-14536: fixed CSI 'M' console command

CSI 'M' deletes lines, but in our vncterm implementation didn't clear properly
the new scrolled lines.

console.c

@@ -1824,7 +1824,8 @@ static void console_putchar(TextConsole *s, int ch)
 		if (s->esc_params[0] == 0)
 		    s->esc_params[0] = 1;
                 scroll_text_cells(s, s->y + s->esc_params[0], s->y, s->sr_bottom - s->y - s->esc_params[0] + 1);
-                update_rect(s, 0, s->y, s->width, s->sr_bottom - s->y + 1);
+                update_rect(s, 0, s->y, s->width, s->sr_bottom - s->y - s->esc_params[0] + 1);
+                clear(s, 0, s->sr_bottom - s->esc_params[0] + 1, s->width, s->esc_params[0]);
 		break;
 	    case 'P':		/* DCH */
 		console_dch(s);