Fix misleading lsp server logs

[dibarbet]

We've gotten a fair number of reports of the language server hanging on startup because the logs look like

Dotnet path: c:\Users\dabarbet\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\7.0.9\dotnet.exe
Activating C# + C# Dev Kit + C# IntelliCode...
info: LanguageServerHost[0]
      Starting server...

This updates the last line to instead indicate that the server has started.