test: http2 connectionListener reject client

This code change modifies connectionListener tests to cover test case
where this.emit('unknownProtocol', socket) returns false

PR-URL: https://github.com/nodejs/node/pull/16080
Ref: https://github.com/nodejs/node/issues/14985


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>