[release/6.0] Use TimeSpan.FromMilliseconds for clientTimeoutInterval in ClientTime… (#39325)

* Use TimeSpan.FromMilliseconds for clientTimeoutInterval in ClientTimeout log
* Update src/SignalR/server/Core/src/HubConnectionContext.cs

Co-authored-by: campersau <buchholz.bastian@googlemail.com>
Co-authored-by: Stephen Halter <halter73@gmail.com>