MULE-7809: Removing test for receivebuffersize. The value is just a sugg...

...estion, so the assertion fails on some environments.
There's no way to determine whether the socket will use or not the hint.
The contract is that you may set the value to whatever you want on the socket factory, and the sockets may or may not use the value you provided based on the network topology, network drivers or runtime considerations.

The change does exactly that. We are removing both the hint and the assertion. The test itself is asserting several other properties. That's why it is still there.