[Security Solution] [AI assistant] Fix bug with running default assistant graph evals (elastic#237996)

## Summary

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gif.

Fix bug where Security Assistant graph evals could not be run because
there was a missing thread ID.

### Checklist

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support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
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[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
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tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
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- [X] If a plugin configuration key changed, check if it needs to be
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- [X] This was checked for breaking HTTP API changes, and any breaking
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used on any tests changed
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Author: KDKHD

x-pack/solutions/security/plugins/elastic_assistant/server/routes/evaluate/post_evaluate.ts

@@ -507,6 +507,9 @@ export const postEvaluateRoute = (
                   {
                     runName,
                     tags: ['evaluation'],
+                    configurable: {
+                      thread_id: uuidv4(),
+                    },
                   }
                 );
                 const lastMessage = result.messages[result.messages.length - 1];