[Proposal] Customize local cluster support in multi data source plugin

[bandinib-amzn]

Is your feature request related to a problem? Please describe.

As a user I don't want local cluster in components supported by multi data source (right now there are three - sample data, dev tool and index pattern). I still want to use local opensearch cluster just for meta data storage, but not for querying.

Describe the solution you'd like

I propose to add new config data_source.defaultCluster (boolean). It's default value would be true. If it is set to False, then remove local cluster from the components supported by multi data source.

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.

[bandinib-amzn]

discussion is in :#5754

[xinruiba]

When data_source.enabled = true and data_source.defaultCluster flag is commented out in yml file , we should by default enable defaultCluster in MD.

Which means:

scenario 1:

data_source.enabled = true
data_source.defaultCluster = true

Then defaultCluster enabled

scenario 2:

data_source.enabled = true
data_source.defaultCluster = false

Then defaultCluster disabled

scenario 3:

data_source.enabled = true
data_source.defaultCluster = undefined

Then defaultCluster should enabled

[bandinib-amzn]

#5827 fixed this. Tracker issue #5754 has been closed.