remove wedge layer from SslStream

[wfurt]

#130366 introduced new layering inside SslStream. This was done to run SslStream on top of the new low-level API to get test coverage and confidence. But the way how it is done have some potential issues and I deferred from comments on the original PR. This is reminder to go clean up the code before code complete for .NET 11. Either we need to finish the integration nicely or we should split the code and have the APIs live separate lives for now.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/ncl, @bartonjs, @vcsjones
See info in area-owners.md if you want to be subscribed.