[Azure.Security.Attestation] net - attestation - tests pipeline is failing

[m-redding]

As part of #46637 I wanted to use the live test pipeline to validate changes were correct. I was unable to do so because the following tests have been failing consistently since June 14th:

• Azure.Security.Attestation.Tests.PolicyGetSetTests(False).AddRemovePolicyManagementCertificate
• Azure.Security.Attestation.Tests.PolicyGetSetTests(False).SetPolicyUnsecuredAad
• Azure.Security.Attestation.Tests.PolicyGetSetTests(True).SetPolicyUnsecuredAad
• Azure.Security.Attestation.Tests.AttestationTests(False).AttestTpmMinimalAad

All of the above tests fail with the error: System.Exception : Attestation token is not yet valid. which looks like is thrown from: https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/attestation/Azure.Security.Attestation/src/AttestationToken.cs#L531

A quick glance at the pipeline history shows that sometimes additional tests fail with this same error as well.

Would be great to get this pipeline more consistently green so it can be used for validation.