[Bug] WithInstanceDiscovery(false) and WithRegion() still hits instance discovery url on airgapped clouds

[bgavrilMS]

Library version used

4.76.0

.NET version

WithInstanceDiscovery(false) and WithRegion() still hits instance discovery url on airgapped clouds

Scenario

ConfidentialClient - service to service (AcquireTokenForClient)

Is this a new or an existing app?

This is a new app or experiment

Issue description and reproduction steps

      IConfidentialClientApplication cca = ConfidentialClientApplicationBuilder.Create("123")
           .WithInstanceDiscovery(false)
           .WithAuthority("https://login.sovcloud.com/tenant/")
           .WithClientSecret("a")
           .WithAzureRegion("reg")
           .Build();

       AuthenticationResult result = await cca.AcquireTokenForClient(["abc"])
           .ExecuteAsync();

Expected: no call to login.microsoftonline.com
Actual: instance discoevry call to login.microsoftonline.com

Relevant code snippets

Expected behavior

No response

Identity provider

Microsoft Entra ID (Work and School accounts and Personal Microsoft accounts)

Regression

No response

Solution and workarounds

No response

[bgavrilMS]

Closing as won't repro. Adding a test to prove it.