Copy iothub connection string sample into smoke test arm template

[benbp]

This is a temporary fix for an issue that causes frequent failures in the smoke tests for azure china cloud. The smoke test test-resources.json ARM template uses a template link which tries to download from github.com. This often fails:

 "message": "Unable to download deployment content from 'https://raw.githubusercontent.com/Azure/azure-sdk-for-net/master/samples/iothub-connect-to-eventhubs/sample-resources.json'. 
The tracking Id is '8bc97f2c-776d-4e04-9518-d92cc78ac6c0'. Please see https://aka.ms/arm-deploy for usage details."

The fix involves copying the linked template into the smoke test template. There is an outstanding feature to add file link support in ARM templates (here). Once that is completed, we can remove this inline update.

Related discussion: #17524 (comment)
Issue to remove this update: #17757

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[benbp]

/check-enforcer override