bugfix: sample: disconnect when all the messages are sent

[ks6088ts]

Description of the problem

Current implementation of the sync version of provision_symmetric_key.py calls disconnect API repeatedly, it seems weird.

Description of the solution

I think it would be correct just as the async version samples/async-hub-scenarios/provision_symmetric_key.py does.

[ks6088ts]

I'm not sure why the CI fails... Mentioning @olivakar , who is checked in the latest update. Could you take a look at it ?

[cartertinney]

I'm not sure why the CI fails... Mentioning @olivakar , who is checked in the latest update. Could you take a look at it ?

Apologies for the late reply - there was an infrastructure issue that broke CI. It has now been addressed, we will take in this fix.

[cartertinney]

/azp run Python E2E

[azure-pipelines[bot]]

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