Remove handshake and update submodule including new tests

Author: nhachicha

driver-core/src/main/com/mongodb/internal/connection/InternalStreamConnectionInitializer.java

@@ -198,8 +198,6 @@ private BsonDocument createHelloCommand(final Authenticator authenticator, final
                 helloCommandDocument.append("speculativeAuthenticate", speculativeAuthenticateDocument);
             }
         }
-        // Add backpressure support indication
-        helloCommandDocument.append("backpressure", BsonBoolean.TRUE);
         return helloCommandDocument;
     }