Avoid "early" access to SqlAuthenticationProviderManager.Instance (#2636)

Author: 0xced

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlInternalConnectionTds.cs

@@ -133,7 +133,6 @@ internal sealed class SqlInternalConnectionTds : SqlInternalConnection, IDisposa
         internal readonly Func<SqlAuthenticationParameters, CancellationToken,Task<SqlAuthenticationToken>> _accessTokenCallback;
 
         private readonly ActiveDirectoryAuthenticationTimeoutRetryHelper _activeDirectoryAuthTimeoutRetryHelper;
-        private readonly SqlAuthenticationProviderManager _sqlAuthenticationProviderManager;
 
         internal bool _cleanSQLDNSCaching = false;
         private bool _serverSupportsDNSCaching = false;
@@ -484,7 +483,6 @@ internal SqlInternalConnectionTds(
             _accessTokenCallback = accessTokenCallback;
 
             _activeDirectoryAuthTimeoutRetryHelper = new ActiveDirectoryAuthenticationTimeoutRetryHelper();
-            _sqlAuthenticationProviderManager = SqlAuthenticationProviderManager.Instance;
 
             _identity = identity;
             Debug.Assert(newSecurePassword != null || newPassword != null, "cannot have both new secure change password and string based change password to be null");
@@ -2362,7 +2360,7 @@ internal SqlFedAuthToken GetFedAuthToken(SqlFedAuthInfo fedAuthInfo)
             // Username to use in error messages.
             string username = null;
 
-            var authProvider = _sqlAuthenticationProviderManager.GetProvider(ConnectionOptions.Authentication);
+            var authProvider = SqlAuthenticationProvider.GetProvider(ConnectionOptions.Authentication);
             if (authProvider == null && _accessTokenCallback == null)
                 throw SQL.CannotFindAuthProvider(ConnectionOptions.Authentication.ToString());