[Bug]: 使用 OBD 白屏部署时，预检查时卡住，无失败项，错误提示 'int' object is not subscriptable

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Describe the bug 官方下载 OceanBase，使用 obd web 白屏部署，卡在了预检查这一步，应该是后端 Python 报错（错误堆栈在下面）

Environment CentOS 8.2 x86_64 OceanBase 4.2.2.0 社区版

Fast Reproduce Steps(Required)

Expected behavior 希望正常安装部署。

Actual Behavior

定位到日志中的 Python 错误堆栈为：

2024-04-23 19:54:26,076 ERROR wrapper (task.py:140) [21beea4e306d4cd7a8afe1418dd427c5] task test got exception
Traceback (most recent call last):
  File "service/common/task.py", line 126, in wrapper
  File "concurrent/futures/_base.py", line 444, in result
  File "concurrent/futures/_base.py", line 389, in __get_result
  File "concurrent/futures/thread.py", line 57, in run
  File "service/handler/deployment_handler.py", line 495, in _precheck
  File "service/handler/deployment_handler.py", line 549, in _do_precheck
  File "_plugin.py", line 305, in _new_func
  File "/home/admin/.obd/plugins/oceanbase-ce/4.2.1.0/generate_config.py", line 350, in generate_config
    disk_free = data_dir_disk['avail']
TypeError: 'int' object is not subscriptable
2024-04-23 19:54:26,077 INFO wrapper (task.py:143) [21beea4e306d4cd7a8afe1418dd427c5] task test finished failed