[BUG] Add datasource with test connect failed

[zhyuanqi]

Describe the bug

Connect failed to remote datasource. After change data_source.ssl.verificationMode: none in config file, connection succeed

To Reproduce
Steps to reproduce the behavior:

1. Go to Datasource
2. Click on Create datasource connection
3. Add a datasource and test connection
4. Datasource connection failed.
5. In the config/opensearch_dashboards.yml file, after change data_source.ssl.verificationMode: none. Connection would work

Expected behavior
Expect test connection to work

Dashboards Version
Main branch

Plugins

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Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Browser and version [e.g. 22]

Additional context

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[BionIT]

The bug is introduced in https://github.com/opensearch-project/OpenSearch-Dashboards/pull/6171/files
The reason is because when passing the sslConfig object, ca field is set to empty array while ca should be optional

[cwperks]

Looks like the default of empty list should be removed here.

This would match the behavior of the existing opensearch_client_config

[cwperks]

@zhyuanqi @BionIT Thank you for filing this issue. I opened a Draft PR to address the issue here: #6282

If the datasource.ssl.certificateAuthorities setting is not present in opensearch_dashboards.yml then the sslConfig portion of the client config should contain undefined instead of empty array.

[kavilla]

@cwperks , looks like this didn't get into 2.13 cut so I have added the label 2.14 and will resolve this issue. If this is incorrect please, update it as needed.

Thank you.

[cwperks]

This is good to be closed. The backport to 2.x was merged yesterday: #6296