bug: Grpc requests go via proxy on Grpc.NET.Client >= 2.44

[prbll]

Yandex.Cloud.SDK 1.4.1
Problem is similar to the one that was fixed in YDB SDK for .NET - ydb-platform/ydb-dotnet-sdk#218.

Grpc.Core.RpcException : Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: Unable to get subchannel from HttpRequestMessage. (proxy_address) InvalidOperationException: Unable to get subchannel from HttpRequestMessage.", DebugException="System.Net.Http.HttpRequestException: Unable to get subchannel from HttpRequestMessage. (proxy_address)")
---- System.Net.Http.HttpRequestException : Unable to get subchannel from HttpRequestMessage. (proxy_address)
-------- System.InvalidOperationException : Unable to get subchannel from HttpRequestMessage.