[hotfix] fix config parse issue when integration with web

[liunaijie]

Purpose of this pull request

fix issue #5700

When inergration with seatunnel-web, In some cases the config file parse will got exception.

Some detail information:
If only define one source ( or one sink ). The ConfigFactory.parseFile() method will parse the source as a SimpleConfigObject instead of SimpleConfigList.
So when we case source as List<Map> will get exception.

This is a hotfix.

Does this PR introduce any user-facing change?

How was this patch tested?

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If you are contributing the connector code, please check that the following files are updated:
  1. Update plugin-mapping.properties and add new connector information in it
  2. Update the pom file of seatunnel-dist
  3. Add ci label in label-scope-conf
  4. Add e2e testcase in seatunnel-e2e
  5. Update connector plugin_config
• Update the release-note.