Fix message history for LangGraphReactAgent and ExternalWorkflow path

[codingbandit]

Fix message history for LangGraphReactAgent and ExternalWorkflow path

The issue or feature being addressed

The LangGraphReactAgent and ExternalWorkflow path execution was not taking into account the conversations enabled property and was always sending in conversation history.

Details on the issue fix or feature implementation

N/A

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• This PR needs to be cherry-picked into at least one release branch
• I have included unit tests for the issue/feature
• I have included inline docs for my changes, where applicable
• I have successfully run a local build
• I have provided the required update scripts, where applicable
• I have updated relevant docs, where applicable