fix: 修复检查MySQL和MariaDB安装的逻辑，确保两者都未安装时才输出错误

linux/usr/local/etc/omc/script/setup.sh

@@ -95,7 +95,7 @@ fi
 
 # =========================
 if [[ "$T_PARAM" == "install" && "$MODE" == "std" ]]; then
-  if ! command -v mysql &> /dev/null || ! command -v mariadb &> /dev/null; then
+  if ! command -v mysql &>/dev/null && ! command -v mariadb &>/dev/null; then
       echo "MySQL or MariaDB not installed"
       exit 1
   fi