SplitHTTP: Fix connection leaks and crashes

[mmmray]

There are a few bugs that are fixed here:

1. (all http versions) When the client opens a connection and closes it without any traffic, the Close would lock forever and not appear on the wire at all
2. (all http versions) When the client terminates the connection correctly, the server would not notice and keep the upload queue and related datastructures around until the proxied connection times out.
3. (quic only) closing the connection might crash the client as well, Fix panic with this error #3699

Are fixed in the following way:

• Problem 1 is addressed by removing the use of LazyReader. It turns out that while ok is being peeked, Close is entirely ignored
• Problem 2 is addressed on the server by using the request's context to close the connection
• Problem 3 is addressed by using the request's context to close the connection instead of Body.Close.

[kabo00os]

This problem occurs with burstObservatory
When several configs are added, sometimes this problem occurs