[Attestation SDK] Hard-coded URL in the test folder

[HarshaNalluru]

Tests pick this hard-coded url https://shareduks.uks.attest.azure.net which represents the "shared provider" in one of the supported regions (UKS in this case). Ideally, the region configured for the test instances is to be used.

Reference - #13120 (comment)

@deyaaeldeen @LarryOsterman

[github-actions]

Hi @HarshaNalluru, we deeply appreciate your input into this project. Regrettably, this issue has remained inactive for over 2 years, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.