[Spring] Use service fqdn to call logstream

[felixatms]

Previously, we get log stream url by modifying test endpoint. Just refactor it to use service fqdn directly in this PR.

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[azure-client-tools-bot-prd]

️✔️Azure CLI Extensions Breaking Change Test

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[azure-client-tools-bot-prd]

Hi @felixsong0824,
Please write the description of changes which can be perceived by customers into HISTORY.rst.
If you want to release a new extension version, please update the version in setup.py as well.

[yonzhan]

Spring