fix: Use universe-domain instead of universe_domain as the MDS en…

…dpoint

Environments will support both endpoints for the foreseeable future.
Closes b/339453829

Src/Support/Google.Apis.Auth/OAuth2/GoogleAuthConsts.cs

@@ -57,7 +57,7 @@ public static class GoogleAuthConsts
         private const string ComputeTokenUrlSuffix = "/computeMetadata/v1/instance/service-accounts/default/token";
         private const string ComputeOidcTokenUrlSuffix = "/computeMetadata/v1/instance/service-accounts/default/identity";
         private const string ComputeDefaultServiceAccountEmailSuffix = "/computeMetadata/v1/instance/service-accounts/default/email";
-        private const string ComputeUniverseDomainUrlSuffix = "/computeMetadata/v1/universe/universe_domain";
+        private const string ComputeUniverseDomainUrlSuffix = "/computeMetadata/v1/universe/universe-domain";
 
         /// <summary>The Compute Engine authorization token server URL</summary>
         /// <remarks>IP address instead of name to avoid DNS resolution</remarks>