Attestation SDK uses deprecated snippet syntax

[heaths]

The snippet syntax //@@ and /*@@*/ is deprecated in favor of:

#if SNIPPET
  Uri uri = new Uri("https://myresource.azure.net");
#else
  Uri uri = TestEnvironment.ResourceUri;
#endif

Please use this new syntax so we can stop supporting the old syntax in snippet-generator. See #20431 for more information.

[pallavit]

@kinelski could we move these to the newer syntax?

[kinelski]

@pallavit